Method and system for authorizing a level of access of a client to a virtual private network connection, based on a client-side attribute

ABSTRACT

An appliance and method for authorizing a level of access of a client to a virtual private network connection, based on a client-side attribute includes the step of establishing, by an appliance, a control connection with a client upon receiving a client request to establish a virtual private network connection with a network. The appliance transmits, via the control connection, a request to the client to evaluate at least one clause of a security string, the at least one clause including an expression associated with a client-side attribute. The client transmits, via the control connection, a response to the appliance comprising a result of evaluating the at least one clause by the client. The appliance assigns the client to an authorization group based on the result of evaluation of the at least one clause.

FIELD OF THE INVENTION

The present invention generally relates to data communication networks. In particular, the present invention relates to a method and system for authorizing a level of access of a client to a virtual private network connection, based on a client-side attribute.

BACKGROUND OF THE INVENTION

Before an endpoint gains access to corporate enterprise network infrastructure and resources, it is increasingly becoming necessary to determine that the endpoint has undergone host security checks and audits to verify that it meets corporate information technology policies. Examples of such checks include, without limitation, verifying that the anti-virus software on the endpoint is up to date, that the latest operating system patches have been installed and that no malicious software is executing on the endpoint. Performing these checks minimizes the infection of other connected corporate assets by a compromised endpoint.

Conventional methods of access control typically require receipt and evaluation of authentication credentials from a client prior to granting access. The credentials are typically presented to an access infrastructure or other security gateway, which determines what types of access may be provided to the client. Methods for requesting and receiving these credentials typically generate additional administrative burdens. For example, if a user is entering the credentials into a user interface, the request for the required credentials must be translated into a format understandable the user, for example from the expression in which the policy was added to a request identifying the explicit credentials required for evaluation of the policy. When the credentials are received from the user, in some methods, a policy engine applies a policy to the credentials in making an access control decision. This typically requires transmission from a component receiving the credentials to the component making the access control decision, generating additional delay in situations where the components are remotely located from each other and from the client.

A method minimizing administrative burden in requesting user credentials by transmitting an expression of a policy to a client without modifying the format of the expression would be desirable. A method for evaluating such an expression by the client, minimizing the number of components required to reach an access control decision would also be desirable.

SUMMARY OF THE INVENTION

In one aspect, a method for authorizing a level of access of a client to a virtual private network connection, based on a client-side attribute includes establishing, by an appliance, a control connection with a client upon receiving a client request to establish a virtual private network connection with a network. The appliance transmits, via the control connection, a request to the client to evaluate at least one clause of a security string, the at least one clause including an expression associated with a client-side attribute. The client transmits, via the control connection, a response to the appliance comprising a result of evaluating the at least one clause by the client. The appliance assigns the client to an authorization group based on the result of evaluation of the at least one clause.

In one embodiment, the appliance transmits the request to evaluate the at least one clause to a collection agent. In another embodiment, the client executes a script to evaluate the at least one clause. In still another embodiment, the client gathers information associated with the client-side attribute. In yet another embodiment, the client evaluates the at least one clause responsive to the gathered information.

In one embodiment, the client identifies a client-side attribute indicating a presence on the client of one of the following: a version of an operating system, a service pack of the operating system, a running service, a running process, and a file. In another embodiment, the client identifies a client-side attribute indicating a presence on the client of one of the following: antivirus software, personal firewall software, anti-spam software, and internet security software. In still another embodiment, the client identifies a client-side attribute identifying a version of one of the following: antivirus software, personal firewall software, anti-spam software, and internet security software.

In one embodiment, the appliance evaluates a second clause of the security string. In another embodiment, the client evaluates a clause of the security string comprising one or more logical operations. In still another embodiment, the appliance transmits the response comprising the result of the evaluation to a policy engine. In yet another embodiment, the appliance assigns the client to the authorization group responsive to an application of a policy by the policy engine to the result of the evaluation.

In one embodiment, the appliance determines that the client lacks a desired client-side attribute, responsive to the result of evaluation of the at least one clause. In another embodiment, the appliance assigns the client to an authorization group providing quarantined access to the network via the appliance. In still another embodiment, the appliance denies a login request from a client if the security string is not associated with an authorization group. In yet another embodiment, the appliance establishes a virtual private network connection with the client in accordance with the authorization group.

In another aspect, a system for authorizing a level of access of a client to a virtual private network connection based on a client-side attribute includes a means for transmitting a request, a request for evaluation of at least one clause of a security string, an evaluation component, a means for transmitting a response to the request, and a means for receiving an assignment to an authorization group. The system comprises a means for transmitting, by a client, a request to an application for a virtual private network connection to a network. The client receives a request, via a control connection between the client and the appliance, for evaluation of at least one clause of a security string, the at least one clause identifying an object for evaluation, an attribute of the object, and a pre-requisite associated with the attribute. An evaluation component on the client identifies the attribute and determines whether the attribute satisfies the pre-requisite, and evaluates the at least one clause. The system comprises a means for transmitting, by the client via the control connection, a response comprising a result of the evaluation of the at least one clause by the evaluation component. The system comprises a means for receiving, from the appliance, an assignment to an authorization group, the assignment determined based on the evaluation of the at least one clause.

In one embodiment, the request received by the client includes at least one clause of a security string, the at least one clause identifying the client as an object for evaluation. In another embodiment, the request received by the client includes at least one clause of a security string, the at least one clause identifying a presence of an application program on the client as an attribute of the object. In still another embodiment, the request received by the client includes at least one clause of a security string, the at least one clause identifying an absence of an application program on the client as an attribute of the object. In yet another embodiment, the request received by the client includes at least one clause of a security string, the at least one clause identifying a presence of a version of an application program on the client as an attribute of the object.

In one embodiment, the request received by the client includes at least one clause of a security string, the at least one clause identifying an absence of a version of an application program on the client as an attribute of the object. In another embodiment, the request received by the client includes at least one clause of a security string, the at least one clause identifying a presence of a required version of an application program on the client as a pre-requisite. In still another embodiment, the request received by the client includes at least one clause of a security string, the at least one clause identifying a presence of an application program on the client as a pre-requisite. In yet another embodiment, the request received by the client includes at least one clause of a security string, the at least one clause identifying an absence of an application program on the client as a pre-requisite.

In one embodiment, the evaluation component executes a script to evaluate the at least one clause. In another embodiment, the evaluation component further comprises a collection agent gathering information associated with the attribute. In still another embodiment, the evaluation component evaluates the at least one clause responsive to the gathered information. In yet another embodiment, the evaluation component is transmitted to the client from the appliance.

In one embodiment, the evaluation component identifies an attribute indicating a presence on the client of one of the following: a version of an operating system, a service pack of the operating system, a running service, a running process, and a file. In another embodiment, the evaluation component identifies an attribute indicating a presence on the client of one of the following: antivirus software, personal firewall software, anti-spam software, and internet security software. In still another embodiment, the evaluation component identifies an attribute identifying a version of one of the following: antivirus software, personal firewall software, anti-spam software, and internet security software. In yet another embodiment, the evaluation component determines that that the attribute satisfies the pre-requisite responsive to the identification of the attribute.

In one embodiment, the means for receiving an assignment further comprises a means for receiving an assignment made responsive to the result of evaluation of a second clause by the appliance. In another embodiment, the means for receiving an assignment further comprises a means for receiving an assignment made responsive to a determination by the appliance that the client lacks a desired attribute. In still another embodiment, the means for receiving an assignment further comprises a means for receiving an assignment to an authorization group providing quarantined access to the network via the appliance. In yet another embodiment, the means for receiving an assignment further comprises a means for receiving a denial, by the appliance, of the client request if the security string is not associated with an authorization group. In a further embodiment, the means for receiving an assignment further comprises a means for receiving an a denial, by the appliance, of the client request if a pre-requisite in the security string is not satisfied

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent and better understood by referring to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1A is a block diagram of an embodiment of a network environment for a client to access a server via an appliance;

FIG. 1B is a block diagram of an embodiment of an environment for delivering a computing environment from a server to a client via an appliance;

FIGS. 1C and 1D are block diagrams of embodiments of a computing device;

FIG. 2A is a block diagram of an embodiment of an appliance for processing communications between a client and a server;

FIG. 2B is a block diagram of another embodiment of an appliance for optimizing, accelerating, load-balancing and routing communications between a client and a server;

FIG. 3 is a block diagram of an embodiment of a client for communicating with a server via the appliance;

FIG. 4A is a block diagram of an embodiment of a network environment providing policy-based access to application programs for a local machine;

FIG. 4B is a block diagram depicting a more detailed embodiment of a policy engine;

FIG. 4C a flow diagram depicting one embodiment of the steps taken by a policy engine to make an access control decision based upon information received about a local machine;

FIG. 5 is a representation of a screen shot depicting one embodiment of an enumeration of scripts to be executed on a client.

FIG. 6 is a flow diagram depicting one embodiment of the steps taken in a method for authorizing a level of access of a client to a virtual private network connection based on a client-side attribute; and

FIG. 7 is a block diagram depicting one embodiment of a system for authorizing a level of access of a client to a virtual private network connection based on a client-side attribute.

The features and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.

DETAILED DESCRIPTION OF THE INVENTION

Prior to discussing the specifics of embodiments of the systems and methods of an appliance and/or client, it may be helpful to discuss the network and computing environments in which such embodiments may be deployed. Referring now to FIG. 1A, an embodiment of a network environment is depicted. In brief overview, the network environment comprises one or more clients 102 a-102 n (also generally referred to as local machine(s) 102, or client(s) 102) in communication with one or more servers 106 a-106 n (also generally referred to as server(s) 106, or remote machine(s) 106) via one or more networks 104, 104′ (generally referred to as network 104). In some embodiments, a client 102 communicates with a server 106 via an appliance 200.

Although FIG. 1A shows a network 104 and a network 104′ between the clients 102 and the servers 106, the clients 102 and the servers 106 may be on the same network 104. The networks 104 and 104′ can be the same type of network or different types of networks. The network 104 and/or the network 104′ can be a local-area network (LAN), such as a company Intranet, a metropolitan area network (MAN), or a wide area network (WAN), such as the Internet or the World Wide Web. In one embodiment, network 104′ may be a private network and network 104 may be a public network. In some embodiments, network 104 may be a private network and network 104′ a public network. In another embodiment, networks 104 and 104′ may both be private networks. In some embodiments, clients 102 may be located at a branch office of a corporate enterprise communicating via a WAN connection over the network 104 to the servers 106 located at a corporate data center.

The network 104 and/or 104′ be any type and/or form of network and may include any of the following: a point to point network, a broadcast network, a wide area network, a local area network, a telecommunications network, a data communication network, a computer network, an ATM (Asynchronous Transfer Mode) network, a SONET (Synchronous Optical Network) network, a SDH (Synchronous Digital Hierarchy) network, a wireless network and a wireline network. In some embodiments, the network 104 may comprise a wireless link, such as an infrared channel or satellite band. The topology of the network 104 and/or 104′ may be a bus, star, or ring network topology. The network 104 and/or 104′ and network topology may be of any such network or network topology as known to those ordinarily skilled in the art capable of supporting the operations described herein.

As shown in FIG. 1A, the appliance 200, which also may be referred to as an interface unit 200 or gateway 200, is shown between the networks 104 and 104′. In some embodiments, the appliance 200 may be located on network 104. For example, a branch office of a corporate enterprise may deploy an appliance 200 at the branch office. In other embodiments, the appliance 200 may be located on network 104′. For example, an appliance 200 may be located at a corporate data center. In yet another embodiment, a plurality of appliances 200 may be deployed on network 104. In some embodiments, a plurality of appliances 200 may be deployed on network 104′. In one embodiment, a first appliance 200 communicates with a second appliance 200′. In other embodiments, the appliance 200 could be a part of any client 102 or server 106 on the same or different network 104,104′ as the client 102. One or more appliances 200 may be located at any point in the network or network communications path between a client 102 and a server 106.

In one embodiment, the system may include multiple, logically-grouped servers 106. In these embodiments, the logical group of servers may be referred to as a server farm 38. In some of these embodiments, the serves 106 may be geographically dispersed. In some cases, a farm 38 may be administered as a single entity. In other embodiments, the server farm 38 comprises a plurality of server farms 38. In one embodiment, the server farm executes one or more applications on behalf of one or more clients 102.

The servers 106 within each farm 38 can be heterogeneous. One or more of the servers 106 can operate according to one type of operating system platform (e.g., WINDOWS NT, manufactured by Microsoft Corp. of Redmond, Wash.), while one or more of the other servers 106 can operate on according to another type of operating system platform (e.g., Unix or Linux). The servers 106 of each farm 38 do not need to be physically proximate to another server 106 in the same farm 38. Thus, the group of servers 106 logically grouped as a farm 38 may be interconnected using a wide-area network (WAN) connection or medium-area network (MAN) connection. For example, a farm 38 may include servers 106 physically located in different continents or different regions of a continent, country, state, city, campus, or room. Data transmission speeds between servers 106 in the farm 38 can be increased if the servers 106 are connected using a local-area network (LAN) connection or some form of direct connection.

Servers 106 may be referred to as a file server, application server, web server, proxy server, or gateway server. In some embodiments, a server 106 may have the capacity to function as either an application server or as a master application server. In one embodiment, a server 106 may include an Active Directory. The clients 102 may also be referred to as client nodes or endpoints. In some embodiments, a client 102 has the capacity to function as both a client node seeking access to applications on a server and as an application server providing access to hosted applications for other clients 102 a-102 n.

In some embodiments, a client 102 communicates with a server 106. In one embodiment, the client 102 communicates directly with one of the servers 106 in a farm 38. In another embodiment, the client 102 executes a program neighborhood application to communicate with a server 106 in a farm 38. In still another embodiment, the server 106 provides the functionality of a master node. In some embodiments, the client 102 communicates with the server 106 in the farm 38 through a network 104. Over the network 104, the client 102 can, for example, request execution of various applications hosted by the servers 106 a-106 n in the farm 38 and receive output of the results of the application execution for display. In some embodiments, only the master node provides the functionality required to identify and provide address information associated with a server 106′ hosting a requested application.

In one embodiment, the server 106 provides functionality of a web server. In another embodiment, the server 106 a receives requests from the client 102, forwards the requests to a second server 106 b and responds to the request by the client 102 with a response to the request from the server 106 b. In still another embodiment, the server 106 acquires an enumeration of applications available to the client 102 and address information associated with a server 106 hosting an application identified by the enumeration of applications. In yet another embodiment, the server 106 presents the response to the request to the client 102 using a web interface. In one embodiment, the client 102 communicates directly with the server 106 to access the identified application. In another embodiment, the client 102 receives application output data, such as display data, generated by an execution of the identified application on the server 106.

Referring now to FIG. 1B, a network environment for delivering and/or operating a computing environment on a client 102 is depicted. In some embodiments, a server 106 includes an application delivery system 190 for delivering a computing environment or an application and/or data file to one or more clients 102. In brief overview, a client 10 is in communication with a server 106 via network 104, 104′ and appliance 200. For example, the client 102 may reside in a remote office of a company, e.g., a branch office, and the server 106 may reside at a corporate data center. The client 102 comprises a client agent 120, and a computing environment 15. The computing environment 15 may execute or operate an application that accesses, processes or uses a data file. The computing environment 15, application and/or data file may be delivered via the appliance 200 and/or the server 106.

In some embodiments, the appliance 200 accelerates delivery of a computing environment 15, or any portion thereof, to a client 102. In one embodiment, the appliance 200 accelerates the delivery of the computing environment 15 by the application delivery system 190. For example, the embodiments described herein may be used to accelerate delivery of a streaming application and data file processable by the application from a central corporate data center to a remote user location, such as a branch office of the company. In another embodiment, the appliance 200 accelerates transport layer traffic between a client 102 and a server 106. The appliance 200 may provide acceleration techniques for accelerating any transport layer payload from a server 106 to a client 102, such as: 1) transport layer connection pooling, 2) transport layer connection multiplexing, 3) transport control protocol buffering, 4) compression and 5) caching. In some embodiments, the appliance 200 provides load balancing of servers 106 in responding to requests from clients 102. In other embodiments, the appliance 200 acts as a proxy or access server to provide access to the one or more servers 106. In another embodiment, the appliance 200 provides a secure virtual private network connection from a first network 104 of the client 102 to the second network 104′ of the server 106, such as an SSL VPN connection. It yet other embodiments, the appliance 200 provides application firewall security, control and management of the connection and communications between a client 102 and a server 106.

In some embodiments, the application delivery management system 190 provides application delivery techniques to deliver a computing environment to a desktop of a user, remote or otherwise, based on a plurality of execution methods and based on any authentication and authorization policies applied via a policy engine 195. With these techniques, a remote user may obtain a computing environment and access to server stored applications and data files from any network connected device 100. In one embodiment, the application delivery system 190 may reside or execute on a server 106. In another embodiment, the application delivery system 190 may reside or execute on a plurality of servers 106 a-106 n. In some embodiments, the application delivery system 190 may execute in a server farm 38. In one embodiment, the server 106 executing the application delivery system 190 may also store or provide the application and data file. In another embodiment, a first set of one or more servers 106 may execute the application delivery system 190, and a different server 106 n may store or provide the application and data file. In some embodiments, each of the application delivery system 190, the application, and data file may reside or be located on different servers. In yet another embodiment, any portion of the application delivery system 190 may reside, execute or be stored on or distributed to the appliance 200, or a plurality of appliances.

The client 102 may include a computing environment 15 for executing an application that uses or processes a data file. The client 102 via networks 104, 104′ and appliance 200 may request an application and data file from the server 106. In one embodiment, the appliance 200 may forward a request from the client 102 to the server 106. For example, the client 102 may not have the application and data file stored or accessible locally. In response to the request, the application delivery system 190 and/or server 106 may deliver the application and data file to the client 102. For example, in one embodiment, the server 106 may transmit the application as an application stream to operate in computing environment 15 on client 102.

In some embodiments, the application delivery system 190 comprises any portion of the Citrix Access Suite™ by Citrix Systems, Inc., such as the MetaFrame or Citrix Presentation Server™ and/or any of the Microsoft® Windows Terminal Services manufactured by the Microsoft Corporation. In one embodiment, the application delivery system 190 may deliver one or more applications to clients 102 or users via a remote-display protocol or otherwise via remote-based or server-based computing. In another embodiment, the application delivery system 190 may deliver one or more applications to clients or users via steaming of the application.

In one embodiment, the application delivery system 190 includes a policy engine 195 for controlling and managing the access to, selection of application execution methods and the delivery of applications. In some embodiments, the policy engine 195 determines the one or more applications a user or client 102 may access. In another embodiment, the policy engine 195 determines how the application should be delivered to the user or client 102, e.g., the method of execution. In some embodiments, the application delivery system 190 provides a plurality of delivery techniques from which to select a method of application execution, such as a server-based computing, streaming or delivering the application locally to the client 120 for local execution.

In one embodiment, a client 102 requests execution of an application program and the application delivery system 190 comprising a server 106 selects a method of executing the application program. In some embodiments, the server 106 receives credentials from the client 102. In another embodiment, the server 106 receives a request for an enumeration of available applications from the client 102. In one embodiment, in response to the request or receipt of credentials, the application delivery system 190 enumerates a plurality of application programs available to the client 102. The application delivery system 190 receives a request to execute an enumerated application. The application delivery system 190 selects one of a predetermined number of methods for executing the enumerated application, for example, responsive to a policy of a policy engine. The application delivery system 190 may select a method of execution of the application enabling the client 102 to receive application-output data generated by execution of the application program on a server 106. The application delivery system 190 may select a method of execution of the application enabling the client 102 to execute the application program locally after retrieving a plurality of application files comprising the application. In yet another embodiment, the application delivery system 190 may select a method of execution of the application to stream the application via the network 104 to the client 102.

A client 102 may execute, operate or otherwise provide an application, which can be any type and/or form of software, program, or executable instructions such as any type and/or form of web browser, web-based client, client-server application, a thin-client computing client, an ActiveX control, or a Java applet, or any other type and/or form of executable instructions capable of executing on client 102. In some embodiments, the application may be a server-based or a remote-based application executed on behalf of the client 102 on a server 106. In one embodiments the server 106 may display output to the client 102 using any thin-client or remote-display protocol, such as the Independent Computing Architecture (ICA) protocol manufactured by Citrix Systems, Inc. of Ft. Lauderdale, Fla. or the Remote Desktop Protocol (RDP) manufactured by the Microsoft Corporation of Redmond, Wash. The application can use any type of protocol and it can be, for example, an HTTP client, an FTP client, an Oscar client, or a Telnet client. In other embodiments, the application comprises any type of software related to VoIP communications, such as a soft IP telephone. In further embodiments, the application comprises any application related to real-time data communications, such as applications for streaming video and/or audio.

In some embodiments, the server 106 or a server farm 38 may be running one or more applications, such as an application providing a thin-client computing or remote display presentation application. In one embodiment, the server 106 or server farm 38 executes as an application, any portion of the Citrix Access Suite™ by Citrix Systems, Inc., such as the MetaFrame or Citrix Presentation Server™, and/or any of the Microsoft® Windows Terminal Services manufactured by the Microsoft Corporation. In one embodiment, the application is an ICA client, developed by Citrix Systems, Inc. of Fort Lauderdale, Fla. In other embodiments, the application includes a Remote Desktop (RDP) client, developed by Microsoft Corporation of Redmond, Wash. Also, the server 106 may run an application, which for example, may be an application server providing email services such as Microsoft Exchange manufactured by the Microsoft Corporation of Redmond, Wash., a web or Internet server, or a desktop sharing server, or a collaboration server. In some embodiments, any of the applications may comprise any type of hosted service or products, such as GoToMeeting™ provided by Citrix Online Division, Inc. of Santa Barbara, Calif., WebEx™ provided by WebEx, Inc. of Santa Clara, Calif., or Microsoft Office Live Meeting provided by Microsoft Corporation of Redmond, Wash.

The client 102, server 106, and appliance 200 may be deployed as and/or executed on any type and form of computing device, such as a computer, network device or appliance capable of communicating on any type and form of network and performing the operations described herein. FIGS. 1C and 1D depict block diagrams of a computing device 100 useful for practicing an embodiment of the client 102, server 106 or appliance 200. As shown in FIGS. 1C and 1D, each computing device 100 includes a central processing unit 121, and a main memory unit 122. As shown in FIG. 1C, a computing device 100 may include a visual display device 124, a keyboard 126 and/or a pointing device 127, such as a mouse. Each computing device 100 may also include additional optional elements, such as one or more input/output devices 130 a-130 b (generally referred to using reference numeral 130), and a cache memory 140 in communication with the central processing unit 121.

The central processing unit 121 is any logic circuitry that responds to and processes instructions fetched from the main memory unit 122. In many embodiments, the central processing unit is provided by a microprocessor unit, such as: those manufactured by Intel Corporation of Mountain View, Calif.; those manufactured by Motorola Corporation of Schaumburg, Ill.; those manufactured by Transmeta Corporation of Santa Clara, Calif.; the RS/6000 processor, those manufactured by International Business Machines of White Plains, N.Y.; or those manufactured by Advanced Micro Devices of Sunnyvale, Calif. The computing device 100 may be based on any of these processors, or any other processor capable of operating as described herein.

Main memory unit 122 may be one or more memory chips capable of storing data and allowing any storage location to be directly accessed by the microprocessor 121, such as Static random access memory (SRAM), Burst SRAM or SynchBurst SRAM (BSRAM), Dynamic random access memory (DRAM), Fast Page Mode DRAM (FPM DRAM), Enhanced DRAM (EDRAM), Extended Data Output RAM (EDO RAM), Extended Data Output DRAM (EDO DRAM), Burst Extended Data Output DRAM (BEDO DRAM), Enhanced DRAM (EDRAM), synchronous DRAM (SDRAM), JEDEC SRAM, PC 100 SDRAM, Double Data Rate SDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), SyncLink DRAM (SLDRAM), Direct Rambus DRAM (DRDRAM), or Ferroelectric RAM (FRAM). The main memory 122 may be based on any of the above described memory chips, or any other available memory chips capable of operating as described herein. In the embodiment shown in FIG. 1C, the processor 121 communicates with main memory 122 via a system bus 150 (described in more detail below). FIG. 1C depicts an embodiment of a computing device 100 in which the processor communicates directly with main memory 122 via a memory port 103. For example, in FIG. 1D the main memory 122 may be DRDRAM.

FIG. 1D depicts an embodiment in which the main processor 121 communicates directly with cache memory 140 via a secondary bus, sometimes referred to as a backside bus. In other embodiments, the main processor 121 communicates with cache memory 140 using the system bus 150. Cache memory 140 typically has a faster response time than main memory 122 and is typically provided by SRAM, BSRAM, or EDRAM. In the embodiment shown in FIG. 1C, the processor 121 communicates with various I/O devices 130 via a local system bus 150. Various busses may be used to connect the central processing unit 121 to any of the I/O devices 130, including a VESA VL bus, an ISA bus, an EISA bus, a MicroChannel Architecture (MCA) bus, a PCI bus, a PCI-X bus, a PCI-Express bus, or a NuBus. For embodiments in which the I/O device is a video display 124, the processor 121 may use an Advanced Graphics Port (AGP) to communicate with the display 124. FIG. 1D depicts an embodiment of a computer 100 in which the main processor 121 communicates directly with I/O device 130 b via HyperTransport, Rapid I/O, or InfiniBand. FIG. 1D also depicts an embodiment in which local busses and direct communication are mixed: the processor 121 communicates with I/O device 130 a using a local interconnect bus while communicating with I/O device 130 b directly.

The computing device 100 may support any suitable installation device 116, such as a floppy disk drive for receiving floppy disks such as 3.5-inch, 5.25-inch disks or ZIP disks, a CD-ROM drive, a CD-R/RW drive, a DVD-ROM drive, tape drives of various formats, USB device, hard-drive or any other device suitable for installing software and programs such as any client agent 120, or portion thereof. The computing device 100 may further comprise a storage device 128, such as one or more hard disk drives or redundant arrays of independent disks, for storing an operating system and other related software, and for storing application software programs such as any program related to the client agent 120. Optionally, any of the installation devices 116 could also be used as the storage device 128. Additionally, the operating system and the software can be run from a bootable medium, for example, a bootable CD, such as KNOPPIX®, a bootable CD for GNU/Linux that is available as a GNU/Linux distribution from knoppix.net.

Furthermore, the computing device 100 may include a network interface 118 to interface to a Local Area Network (LAN), Wide Area Network (WAN) or the Internet through a variety of connections including, but not limited to, standard telephone lines, LAN or WAN links (e.g., 802.11, T1, T3, 56 kb, X.25), broadband connections (e.g., ISDN, Frame Relay, ATM), wireless connections, or some combination of any or all of the above. The network interface 118 may comprise a built-in network adapter, network interface card, PCMCIA network card, card bus network adapter, wireless network adapter, USB network adapter, modem or any other device suitable for interfacing the computing device 100 to any type of network capable of communication and performing the operations described herein. A wide variety of I/O devices 1106 a-1106 n may be present in the computing device 100. Input devices include keyboards, mice, trackpads, trackballs, microphones, and drawing tablets. Output devices include video displays, speakers, inkjet printers, laser printers, and dye-sublimation printers. The I/O devices may be controlled by an I/O controller 123 as shown in FIG. 1C. The I/O controller may control one or more I/O devices such as a keyboard 126 and a pointing device 127, e.g., a mouse or optical pen. Furthermore, an I/O device may also provide storage 128 and/or an installation medium 116 for the computing device 100. In still other embodiments, the computing device 100 may provide USB connections to receive handheld USB storage devices such as the USB Flash Drive line of devices manufactured by Twintech Industry, Inc. of Los Alamitos, Calif.

In some embodiments, the computing device 100 may comprise or be connected to multiple display devices 124 a-124 n, which each may be of the same or different type and/or form. As such, any of the I/O devices 130 a-130 n and/or the I/O controller 123 may comprise any type and/or form of suitable hardware, software, or combination of hardware and software to support, enable or provide for the connection and use of multiple display devices 124 a-124 n by the computing device 100. For example, the computing device 100 may include any type and/or form of video adapter, video card, driver, and/or library to interface, communicate, connect or otherwise use the display devices 124 a-124 n. In one embodiment, a video adapter may comprise multiple connectors to interface to multiple display devices 124 a-124 n. In other embodiments, the computing device 100 may include multiple video adapters, with each video adapter connected to one or more of the display devices 124 a-124 n. In some embodiments, any portion of the operating system of the computing device 100 may be configured for using multiple displays 124 a-124 n. In other embodiments, one or more of the display devices 124 a-124 n may be provided by one or more other computing devices, such as computing devices 100 a and 100 b connected to the computing device 100, for example, via a network. These embodiments may include any type of software designed and constructed to use another computer's display device as a second display device 124 a for the computing device 100. One ordinarily skilled in the art will recognize and appreciate the various ways and embodiments that a computing device 100 may be configured to have multiple display devices 124 a-124 n.

In further embodiments, an I/O device 130 may be a bridge 170 between the system bus 150 and an external communication bus, such as a USB bus, an Apple Desktop Bus, an RS-232 serial connection, a SCSI bus, a FireWire bus, a FireWire 800 bus, an Ethernet bus, an AppleTalk bus, a Gigabit Ethernet bus, an Asynchronous Transfer Mode bus, a HIPPI bus, a Super HIPPI bus, a SerialPlus bus, a SCI/LAMP bus, a FibreChannel bus, or a Serial Attached small computer system interface bus.

A computing device 100 of the sort depicted in FIGS. 1C and 1D typically operate under the control of operating systems, which control scheduling of tasks and access to system resources. The computing device 100 can be running any operating system such as any of the versions of the Microsoft® Windows operating systems, the different releases of the Unix and Linux operating systems, any version of the Mac OS® for Macintosh computers, any embedded operating system, any real-time operating system, any open source operating system, any proprietary operating system, any operating systems for mobile computing devices, or any other operating system capable of running on the computing device and performing the operations described herein. Typical operating systems include: WINDOWS 3.x, WINDOWS 95, WINDOWS 98, WINDOWS 2000, WINDOWS NT 3.51, WINDOWS NT 4.0, WINDOWS CE, and WINDOWS XP, all of which are manufactured by Microsoft Corporation of Redmond, Wash.; MacOS, manufactured by Apple Computer of Cupertino, Calif.; OS/2, manufactured by International Business Machines of Armonk, N.Y.; and Linux, a freely-available operating system distributed by Caldera Corp. of Salt Lake City, Utah, or any type and/or form of a Unix operating system, among others.

In other embodiments, the computing device 100 may have different processors, operating systems, and input devices consistent with the device. For example, in one embodiment the computer 100 is a Treo 180, 270, 1060, 600 or 650 smart phone manufactured by Palm, Inc. In this embodiment, the Treo smart phone is operated under the control of the PalmOS operating system and includes a stylus input device as well as a five-way navigator device. Moreover, the computing device 100 can be any workstation, desktop computer, laptop or notebook computer, server, handheld computer, mobile telephone, any other computer, or other form of computing or telecommunications device that is capable of communication and that has sufficient processor power and memory capacity to perform the operations described herein.

FIG. 2A is a block diagram depicting one embodiment of an appliance 200. The architecture of the appliance 200 in FIG. 2A is provided by way of illustration only and is not intended to be limiting. As shown in FIG. 2, appliance 200 comprises a hardware layer 206 and a software layer divided into a user space 202 and a kernel space 204.

Hardware layer 206 provides the hardware elements upon which programs and services within kernel space 204 and user space 202 are executed. Hardware layer 206 also provides the structures and elements which allow programs and services within kernel space 204 and user space 202 to communicate data both internally and externally with respect to appliance 200. As shown in FIG. 2, the hardware layer 206 includes a processing unit 262 for executing software programs and services, a memory 264 for storing software and data, network ports 266 for transmitting and receiving data over a network, and an encryption processor 260 for performing functions related to Secure Sockets Layer processing of data transmitted and received over the network. In some embodiments, the central processing unit 262 may perform the functions of the encryption processor 260 in a single processor. Additionally, the hardware layer 206 may comprise multiple processors for each of the processing unit 262 and the encryption processor 260. The processor 262 may include any of the processors 121 described above in connection with FIGS. 1C and 1D. In some embodiments, the central processing unit 262 may perform the functions of the encryption processor 260 in a single processor. Additionally, the hardware layer 206 may comprise multiple processors for each of the processing unit 262 and the encryption processor 260. For example, in one embodiment, the appliance 200 comprises a first processor 262 and a second processor 262′. In other embodiments, the processor 262 or 262′ comprises a multi-core processor.

Although the hardware layer 206 of appliance 200 is generally illustrated with an encryption processor 260, processor 260 may be a processor for performing functions related to any encryption protocol, such as the Secure Socket Layer (SSL) or Transport Layer Security (TLS) protocol. In some embodiments, the processor 260 may be a general purpose processor (GPP), and in further embodiments, may be have executable instructions for performing processing of any security related protocol.

Although the hardware layer 206 of appliance 200 is illustrated with certain elements in FIG. 2, the hardware portions or components of appliance 200 may comprise any type and form of elements, hardware or software, of a computing device, such as the computing device 100 illustrated and discussed herein in conjunction with FIGS. 1C and 1D. In some embodiments, the appliance 200 may comprise a server, gateway, router, switch, bridge or other type of computing or network device, and have any hardware and/or software elements associated therewith.

The operating system of appliance 200 allocates, manages, or otherwise segregates the available system memory into kernel space 204 and user space 204. In example software architecture 200, the operating system may be any type and/or form of Unix operating system although the invention is not so limited. As such, the appliance 200 can be running any operating system such as any of the versions of the Microsoft® Windows operating systems, the different releases of the Unix and Linux operating systems, any version of the Mac OS® for Macintosh computers, any embedded operating system, any network operating system, any real-time operating system, any open source operating system, any proprietary operating system, any operating systems for mobile computing devices or network devices, or any other operating system capable of running on the appliance 200 and performing the operations described herein.

The kernel space 204 is reserved for running the kernel 230, including any device drivers, kernel extensions or other kernel related software. As known to those skilled in the art, the kernel 230 is the core of the operating system, and provides access, control, and management of resources and hardware-related elements of the appliance 200. In accordance with an embodiment of the appliance 200, the kernel space 204 also includes a number of network services or processes working in conjunction with a cache manager 232, sometimes also referred to as the integrated cache, the benefits of which are described in detail further herein. Additionally, the embodiment of the kernel 230 will depend on the embodiment of the operating system installed, configured, or otherwise used by the device 200.

In one embodiment, the device 200 comprises one network stack 267, such as a TCP/IP based stack, for communicating with the client 102 and/or the server 106. In one embodiment, the network stack 267 is used to communicate with a first network, such as network 104, and with a second network 104′. In some embodiments, the appliance 200 terminates a first transport layer connection, such as a TCP connection of a client 102, and establishes a second transport layer connection to a server 106 for use by the client 102, e.g., the second transport layer connection is terminated at the appliance 200 and the server 106. The first and second transport layer connections may be established via a single network stack 267. In other embodiments, the appliance 200 may comprise multiple network stacks, for example 267 and 267′, and the first transport layer connection may be established or terminated at one network stack 267, and the second transport layer connection on the second network stack 267′. For example, one network stack may be for receiving and transmitting network packet on a first network, and another network stack for receiving and transmitting network packets on a second network. In one embodiment, the network stack 267 comprises a buffer 243 for queuing one or more network packets for transmission by the appliance 200.

As shown in FIG. 2, the kernel space 204 includes the cache manager 232, a high-speed layer 2-7 integrated packet engine 240, an encryption engine 234, a policy engine 236 and multi-protocol compression logic 238. Running these components or processes 232, 240, 234, 236 and 238 in kernel space 204 or kernel mode instead of the user space 202 improves the performance of each of these components, alone and in combination. Kernel operation means that these components or processes 232, 240, 234, 236 and 238 run in the core address space of the operating system of the appliance 200. For example, running the encryption engine 234 in kernel mode improves encryption performance by moving encryption and decryption operations to the kernel, thereby reducing the number of transitions between the memory space or a kernel thread in kernel mode and the memory space or a thread in user mode. For example, data obtained in kernel mode may not need to be passed or copied to a process or thread running in user mode, such as from a kernel level data structure to a user level data structure. In another aspect, the number of context switches between kernel mode and user mode are also reduced. Additionally, synchronization of and communications between any of the components or processes 232, 240, 235, 236 and 238 can be performed more efficiently in the kernel space 204.

In some embodiments, any portion of the components 232, 240, 234, 236 and 238 may run or operate in the kernel space 204, while other portions of these components 232, 240, 234, 236 and 238 may run or operate in user space 202. In one embodiment, the appliance 200 uses a kernel-level data structure providing access to any portion of one or more network packets, for example, a network packet comprising a request from a client 102 or a response from a server 106. In some embodiments, the kernel-level data structure may be obtained by the packet engine 240 via a transport layer driver interface or filter to the network stack 267. The kernel-level data structure may comprise any interface and/or data accessible via the kernel space 204 related to the network stack 267, network traffic or packets received or transmitted by the network stack 267. In other embodiments, the kernel-level data structure may be used by any of the components or processes 232, 240, 234, 236 and 238 to perform the desired operation of the component or process. In one embodiment, a component 232, 240, 234, 236 and 238 is running in kernel mode 204 when using the kernel-level data structure, while in another embodiment, the component 232, 240, 234, 236 and 238 is running in user mode when using the kernel-level data structure. In some embodiments, the kernel-level data structure may be copied or passed to a second kernel-level data structure, or any desired user-level data structure.

The cache manager 232 may comprise software, hardware or any combination of software and hardware to provide cache access, control and management of any type and form of content, such as objects or dynamically generated objects served by the originating servers 106. The data, objects or content processed and stored by the cache manager 232 may comprise data in any format, such as a markup language, or communicated via any protocol. In some embodiments, the cache manager 232 duplicates original data stored elsewhere or data previously computed, generated or transmitted, in which the original data may require longer access time to fetch, compute or otherwise obtain relative to reading a cache memory element. Once the data is stored in the cache memory element, future use can be made by accessing the cached copy rather than refetching or recomputing the original data, thereby reducing the access time. In some embodiments, the cache memory element nat comprise a data object in memory 264 of appliance 200. In other embodiments, the cache memory element may comprise memory having a faster access time than memory 264. In another embodiment, the cache memory element may comprise any type and form of storage element of the appliance 200, such as a portion of a hard disk. In some embodiments, the processing unit 262 may provide cache memory for use by the cache manager 232. In yet further embodiments, the cache manager 232 may use any portion and combination of memory, storage, or the processing unit for caching data, objects, and other content.

Furthermore, the cache manager 232 includes any logic, functions, rules, or operations to perform any embodiments of the techniques of the appliance 200 described herein. For example, the cache manager 232 includes logic or functionality to invalidate objects based on the expiration of an invalidation time period or upon receipt of an invalidation command from a client 102 or server 106. In some embodiments, the cache manager 232 may operate as a program, service, process or task executing in the kernel space 204, and in other embodiments, in the user space 202. In one embodiment, a first portion of the cache manager 232 executes in the user space 202 while a second portion executes in the kernel space 204. In some embodiments, the cache manager 232 can comprise any type of general purpose processor (GPP), or any other type of integrated circuit, such as a Field Programmable Gate Array (FPGA), Programmable Logic Device (PLD), or Application Specific Integrated Circuit (ASIC).

The policy engine 236 may include, for example, an intelligent statistical engine or other programmable application(s). In one embodiment, the policy engine 236 provides a configuration mechanism to allow a user to identifying, specify, define or configure a caching policy. Policy engine 236, in some embodiments, also has access to memory to support data structures such as lookup tables or hash tables to enable user-selected caching policy decisions. In other embodiments, the policy engine 236 may comprise any logic, rules, functions or operations to determine and provide access, control and management of objects, data or content being cached by the appliance 200 in addition to access, control and management of security, network traffic, network access, compression or any other function or operation performed by the appliance 200. Further examples of specific caching policies are further described herein.

The encryption engine 234 comprises any logic, business rules, functions or operations for handling the processing of any security related protocol, such as SSL or TLS, or any function related thereto. For example, the encryption engine 234 encrypts and decrypts network packets, or any portion thereof, communicated via the appliance 200. The encryption engine 234 may also setup or establish SSL or TLS connections on behalf of the client 102 a-102 n, server 106 a-106 n, or appliance 200. As such, the encryption engine 234 provides offloading and acceleration of SSL processing. In one embodiment, the encryption engine 234 uses a tunneling protocol to provide a virtual private network between a client 102 a-102 n and a server 106 a-106 n. In some embodiments, the encryption engine 234 is in communication with the encryption processor 260. In other embodiments, the encryption engine 234 comprises executable instructions running on the encryption processor 260.

The multi-protocol compression engine 238 comprises any logic, business rules, function or operations for compressing one or more protocols of a network packet, such as any of the protocols used by the network stack 267 of the device 200. In one embodiment, multi-protocol compression engine 238 compresses bi-directionally between clients 102 a-102 n and servers 106 a-106 n any TCP/IP based protocol, including Messaging Application Programming Interface (MAPI) (email), File Transfer Protocol (FTP), HyperText Transfer Protocol (HTTP), Common Internet File System (CIFS) protocol (file transfer), Independent Computing Architecture (ICA) protocol, Remote Desktop Protocol (RDP), Wireless Application Protocol (WAP), Mobile IP protocol, and Voice Over IP (VoIP) protocol. In other embodiments, multi-protocol compression engine 238 provides compression of Hypertext Markup Language (HTML) based protocols and in some embodiments, provides compression of any markup languages, such as the Extensible Markup Language (XML). In one embodiment, the multi-protocol compression engine 238 provides compression of any high-performance protocol, such as any protocol designed for appliance 200 to appliance 200 communications. In another embodiment, the multi-protocol compression engine 238 compresses any payload of or any communication using a modified transport control protocol, such as Transaction TCP (T/TCP), TCP with selection acknowledgements (TCP-SACK), TCP with large windows (TCP-LW), a congestion prediction protocol such as the TCP-Vegas protocol, and a TCP spoofing protocol.

As such, the multi-protocol compression engine 238 accelerates performance for users accessing applications via desktop clients, e.g., Microsoft Outlook and non-Web thin clients, such as any client launched by popular enterprise applications like Oracle, SAP and Siebel, and even mobile clients, such as the Pocket PC. In some embodiments, the multi-protocol compression engine 238 by executing in the kernel mode 204 and integrating with packet processing engine 240 accessing the network stack 267 is able to compress any of the protocols carried by the TCP/IP protocol, such as any application layer protocol.

High speed layer 2-7 integrated packet engine 240, also generally referred to as a packet processing engine or packet engine, is responsible for managing the kernel-level processing of packets received and transmitted by appliance 200 via network ports 266. The high speed layer 2-7 integrated packet engine 240 may comprise a buffer for queuing one or more network packets during processing, such as for receipt of a network packet or transmission of a network packer. Additionally, the high speed layer 2-7 integrated packet engine 240 is in communication with one or more network stacks 267 to send and receive network packets via network ports 266. The high speed layer 2-7 integrated packet engine 240 works in conjunction with encryption engine 234, cache manager 232, policy engine 236 and multi-protocol compression logic 238. In particular, encryption engine 234 is configured to perform SSL processing of packets, policy engine 236 is configured to perform functions related to traffic management such as request-level content switching and request-level cache redirection, and multi-protocol compression logic 238 is configured to perform functions related to compression and decompression of data.

The high speed layer 2-7 integrated packet engine 240 includes a packet processing timer 242. In one embodiment, the packet processing timer 242 provides one or more time intervals to trigger the processing of incoming, i.e., received, or outgoing, i.e., transmitted, network packets. In some embodiments, the high speed layer 2-7 integrated packet engine 240 processes network packets responsive to the timer 242. The packet processing timer 242 provides any type and form of signal to the packet engine 240 to notify, trigger, or communicate a time related event, interval or occurrence. In many embodiments, the packet processing timer 242 operates in the order of milliseconds, such as for example 100 ms, 50 ms or 25 ms. For example, in some embodiments, the packet processing timer 242 provides time intervals or otherwise causes a network packet to be processed by the high speed layer 2-7 integrated packet engine 240 at a 10 ms time interval, while in other embodiments, at a 5 ms time interval, and still yet in further embodiments, as short as a 3, 2, or 1 ms time interval. The high speed layer 2-7 integrated packet engine 240 may be interfaced, integrated or in communication with the encryption engine 234, cache manager 232, policy engine 236 and multi-protocol compression engine 238 during operation. As such, any of the logic, functions, or operations of the encryption engine 234, cache manager 232, policy engine 236 and multi-protocol compression logic 238 may be performed responsive to the packet processing timer 242 and/or the packet engine 240. Therefore, any of the logic, functions, or operations of the encryption engine 234, cache manager 232, policy engine 236 and multi-protocol compression logic 238 may be performed at the granularity of time intervals provided via the packet processing timer 242, for example, at a time interval of less than or equal to 10 ms. For example, in one embodiment, the cache manager 232 may perform invalidation of any cached objects responsive to the high speed layer 2-7 integrated packet engine 240 and/or the packet processing timer 242. In another embodiment, the expiry or invalidation time of a cached object can be set to the same order of granularity as the time interval of the packet processing timer 242, such as at every 10 ms.

In contrast to kernel space 204, user space 202 is the memory area or portion of the operating system used by user mode applications or programs otherwise running in user mode. A user mode application may not access kernel space 204 directly and uses service calls in order to access kernel services. As shown in FIG. 2, user space 202 of appliance 200 includes a graphical user interface (GUI) 210, a command line interface (CLI) 212, shell services 214, health monitoring program 216, and daemon services 218. GUI 210 and CLI 212 provide a means by which a system administrator or other user can interact with and control the operation of appliance 200, such as via the operating system of the appliance 200 and either is user space 202 or kernel space 204. The GUI 210 may be any type and form of graphical user interface and may be presented via text, graphical or otherwise, by any type of program or application, such as a browser. The CLI 212 may be any type and form of command line or text-based interface, such as a command line provided by the operating system. For example, the CLI 212 may comprise a shell, which is a tool to enable users to interact with the operating system. In some embodiments, the CLI 212 may be provided via a bash, csh, tcsh, or ksh type shell. The shell services 214 comprises the programs, services, tasks, processes or executable instructions to support interaction with the appliance 200 or operating system by a user via the GUI 210 and/or CLI 212.

Health monitoring program 216 is used to monitor, check, report and ensure that network systems are functioning properly and that users are receiving requested content over a network. Health monitoring program 216 comprises one or more programs, services, tasks, processes or executable instructions to provide logic, rules, functions or operations for monitoring any activity of the appliance 200. In some embodiments, the health monitoring program 216 intercepts and inspects any network traffic passed via the appliance 200. In other embodiments, the health monitoring program 216 interfaces by any suitable means and/or mechanisms with one or more of the following: the encryption engine 234, cache manager 232, policy engine 236, multi-protocol compression logic 238, packet engine 240, daemon services 218, and shell services 214. As such, the health monitoring program 216 may call any application programming interface (API) to determine a state, status, or health of any portion of the appliance 200. For example, the health monitoring program 216 may ping or send a status inquiry on a periodic basis to check if a program, process, service or task is active and currently running. In another example, the health monitoring program 216 may check any status, error or history logs provided by any program, process, service or task to determine any condition, status or error with any portion of the appliance 200.

Daemon services 218 are programs that run continuously or in the background and handle periodic service requests received by appliance 200. In some embodiments, a daemon service may forward the requests to other programs or processes, such as another daemon service 218 as appropriate. As known to those skilled in the art, a daemon service 218 may run unattended to perform continuous or periodic system wide functions, such as network control, or to perform any desired task. In some embodiments, one or more daemon services 218 run in the user space 202, while in other embodiments, one or more daemon services 218 run in the kernel space.

Referring now to FIG. 2B, a block diagram depicts another embodiment of the appliance 200. In brief overview, the appliance 200 provides one or more of the following services, functionality or operations: SSL VPN connectivity 280, switching/load balancing 284, Domain Name Service resolution 286, acceleration 288 and an application firewall 290 for communications between one or more clients 102 and one or more servers 106. In one embodiment, the appliance 200 comprises any of the network devices manufactured by Citrix Systems, Inc. of Ft. Lauderdale Fla., referred to as Citrix NetScaler devices. Each of the servers 106 may provide one or more network related services 270 a-270 n (referred to as services 270). For example, a server 106 may provide an http service 270. The appliance 200 comprises one or more virtual servers or virtual internet protocol servers, referred to as a vServer, VIP server, or just VIP 275 a-275 n (also referred to herein as vServer 275). The vServer 275 receives, intercepts or otherwise processes communications between a client 102 and a server 106 in accordance with the configuration and operations of the appliance 200.

The vServer 275 may comprise software, hardware or any combination of software and hardware. The vServer 275 may comprise any type and form of program, service, task, process or executable instructions operating in user mode 202, kernel mode 204 or any combination thereof in the appliance 200. The vServer 275 includes any logic, functions, rules, or operations to perform any embodiments of the techniques described herein, such as SSL VPN 280, switching/load balancing 284, Domain Name Service resolution 286, acceleration 288 and an application firewall 290. In some embodiments, the vServer 275 establishes a connection to a service 270 of a server 106. The service 275 may comprise any program, application, process, task or set of executable instructions capable of connecting to and communicating to the appliance 200, client 102 or vServer 275. For example, the service 270 may comprise a web server, http server, ftp, email or database server. In some embodiments, the service 270 is a daemon process or network driver for listening, receiving and/or sending communications for an application, such as email, database or an enterprise application. In some embodiments, the service 270 may communicate on a specific IP address, or IP address and port.

In some embodiments, the vServer 275 applies one or more policies of the policy engine 236 to network communications between the client 102 and server 106. In one embodiment, the policies are associated with a vServer 275. In another embodiment, the policies are based on a user, or a group of users. In yet another embodiment, a policy is global and applies to one or more vServers 275 a-275 n, and any user or group of users communicating via the appliance 200. In some embodiments, the policies of the policy engine have conditions upon which the policy is applied based on any content of the communication, such as internet protocol address, port, protocol type, header or fields in a packet, or the context of the communication, such as user, group of the user, vServer 275, transport layer connection, and/or identification or attributes of the client 102 or server 106.

In other embodiments, the appliance 200 communicates or interfaces with the policy engine 236 to determine authentication and/or authorization of a remote user or a remote client 102 to access the computing environment 15, application, and/or data file from a server 106. In another embodiment, the appliance 200 communicates or interfaces with the policy engine 236 to determine authentication and/or authorization of a remote user or a remote client 102 to have the application delivery system 190 deliver one or more of the computing environment 15, application, and/or data file. In yet another embodiment, the appliance 200 establishes a VPN or SSL VPN connection based on the policy engine's 236 authentication and/or authorization of a remote user or a remote client 102. In one embodiment, the appliance 200 controls the flow of network traffic and communication sessions based on policies of the policy engine 236. For example, the appliance 200 may control the access to a computing environment 15, application or data file based on the policy engine 236.

In some embodiments, the vServer 275 establishes a transport layer connection, such as a TCP or UDP connection with a client 102 via the client agent 120. In one embodiment, the vServer 275 listens for and receives communications from the client 102. In other embodiments, the vServer 275 establishes a transport layer connection, such as a TCP or UDP connection with a server 106. In one embodiment, the vServer 275 establishes the transport layer connection to an internet protocol address and port of a server 270 running on the server 106. In another embodiment, the vServer 275 associates a first transport layer connection to a client 102 with a second transport layer connection to the server 106. In some embodiments, a vServer 275 establishes a pool of transport layer connections to a server 106 and multiplexes client requests via the pooled transport layer connections.

In some embodiments, the appliance 200 provides an SSL VPN connection 280 between a client 102 and a server 106. For example, a client 102 on a first network 104 requests to establish a connection to a server 106 on a second network 104′. In some embodiments, the second network 104′ is not routable from the first network 104. In other embodiments, the client 102 is on a public network 104 and the server 106 is on a private network 104′, such as a corporate network. In one embodiment, the client agent 120 intercepts communications of the client 102 on the first network 104, encrypts the communications, and transmits the communications via a first transport layer connection to the appliance 200. The appliance 200 associates the first transport layer connection on the first network 104 to a second transport layer connection to the server 106 on the second network 104. The appliance 200 receives the intercepted communication from the client agent 102, decrypts the communications, and transmits the communication to the server 106 on the second network 104 via the second transport layer connection. The second transport layer connection may be a pooled transport layer connection. As such, the appliance 200 provides an end-to-end secure transport layer connection for the client 102 between the two networks 104, 104′.

In one embodiment, the appliance 200 hosts an intranet internet protocol, or intranetIP, 282 address of the client 102 on the virtual private network 104. The client 102 has a local network identifier, such as an internet protocol (IP) address and/or host name on the first network 104. When connected to the second network 104′ via the appliance 200, the appliance 200 establishes, assigns or otherwise provides an IntranetIP, which is a network identifier, such as IP address and/or host name, for the client 102 on the second network 104′. The appliance 200 listens for and receives on the second or private network 104′ any communications directed towards the client 102 using the client's established IntranetIP 282. In one embodiment, the appliance 200 acts as or on behalf of the client 102 on the second private network 104. For example, in another embodiment, a vServer 275 listens for and responds to communications to the IntranetIP 282 of the client 102. In some embodiments, if a computing device 100 on the second network 104′ transmits a request, the appliance 200 processes the request as if it were the client 102. For example, the appliance 200 may respond to a ping to the client's IntranetIP 282. In another example, the appliance may establish a connection, such as a TCP or UDP connection, with computing device 100 on the second network 104 requesting a connection with the client's IntranetIP 282.

In some embodiments, the appliance 200 provides one or more of the following acceleration techniques 288 to communications between the client 102 and server 106: 1) compression; 2) decompression; 3) Transmission Control Protocol pooling; 4) Transmission Control Protocol multiplexing; 5) Transmission Control Protocol buffering; and 6) caching. In one embodiment, the appliance 200 relieves servers 106 of much of the processing load caused by repeatedly opening and closing transport layers connections to clients 102 by opening one or more transport layer connections with each server 106 and maintaining these connections to allow repeated data accesses by clients via the Internet. This technique is referred to herein as “connection pooling”.

In some embodiments, in order to seamlessly splice communications from a client 102 to a server 106 via a pooled transport layer connection, the appliance 200 translates or multiplexes communications by modifying sequence number and acknowledgment numbers at the transport layer protocol level. This is referred to as “connection multiplexing”. In some embodiments, no application layer protocol interaction is required. For example, in the case of an in-bound packet (that is, a packet received from a client 102), the source network address of the packet is changed to that of an output port of appliance 200, and the destination network address is changed to that of the intended server. In the case of an outbound packet (that is, one received from a server 106), the source network address is changed from that of the server 106 to that of an output port of appliance 200 and the destination address is changed from that of appliance 200 to that of the requesting client 102. The sequence numbers and acknowledgment numbers of the packet are also translated to sequence numbers and acknowledgement expected by the client 102 on the appliance's 200 transport layer connection to the client 102. In some embodiments, the packet checksum of the transport layer protocol is recalculated to account for these translations.

In another embodiment, the appliance 200 provides switching or load-balancing functionality 284 for communications between the client 102 and server 106. In some embodiments, the appliance 200 distributes traffic and directs client requests to a server 106 based on layer 4 or application-layer request data. In one embodiment, although the network layer or layer 2 of the network packet identifies a destination server 106, the appliance 200 determines the server 106 to distribute the network packet by application information and data carried as payload of the transport layer packet. In one embodiment, the health monitoring programs 216 of the appliance 200 monitor the health of servers to determine the server 106 for which to distribute a client's request. In some embodiments, if the appliance 200 detects a server 106 is not available or has a load over a predetermined threshold, the appliance 200 can direct or distribute client requests to another server 106.

In some embodiments, the appliance 200 acts as a Domain Name Service (DNS) resolver or otherwise provides resolution of a DNS request from clients 102. In some embodiments, the appliance intercepts' a DNS request transmitted by the client 102. In one embodiment, the appliance 200 responds to a client's DNS request with an IP address of or hosted by the appliance 200. In this embodiment, the client 102 transmits network communication for the domain name to the appliance 200. In another embodiment, the appliance 200 responds to a client's DNS request with an IP address of or hosted by a second appliance 200′. In some embodiments, the appliance 200 responds to a client's DNS request with an IP address of a server 106 determined by the appliance 200.

In yet another embodiment, the appliance 200 provides application firewall functionality 290 for communications between the client 102 and server 106. In one embodiment, the policy engine 236 provides rules for detecting and blocking illegitimate requests. In some embodiments, the application firewall 290 protects against denial of service (DoS) attacks. In other embodiments, the appliance inspects the content of intercepted requests to identify and block application-based attacks. In some embodiments, the rules/policy engine 236 comprises one or more application firewall or security control policies for providing protections against various classes and types of web or Internet based vulnerabilities, such as one or more of the following: 1) buffer overflow, 2) CGI-BIN parameter manipulation, 3) form/hidden field manipulation, 4) forceful browsing, 5) cookie or session poisoning, 6) broken access control list (ACLs) or weak passwords, 7) cross-site scripting (XSS), 8) command injection, 9) SQL injection, 10) error triggering sensitive information leak, 11) insecure use of cryptography, 12) server misconfiguration, 13) back doors and debug options, 14) website defacement, 15) platform or operating systems vulnerabilities, and 16) zero-day exploits. In an embodiment, the application firewall 290 provides HTML form field protection in the form of inspecting or analyzing the network communication for one or more of the following: 1) required fields are returned, 2) no added field allowed, 3) read-only and hidden field enforcement, 4) drop-down list and radio button field conformance, and 5) form-field max-length enforcement. In some embodiments, the application firewall 290 ensures cookies are not modified. In other embodiments, the application firewall 290 protects against forceful browsing by enforcing legal URLs.

In still yet other embodiments, the application firewall 290 protects any confidential information contained in the network communication. The application firewall 290 may inspect or analyze any network communication in accordance with the rules or polices of the engine 236 to identify any confidential information in any field of the network packet. In some embodiments, the application firewall 290 identifies in the network communication one or more occurrences of a credit card number, password, social security number, name, patient code, contact information, and age. The encoded portion of the network communication may comprise these occurrences or the confidential information. Based on these occurrences, in one embodiment, the application firewall 290 may take a policy action on the network communication, such as prevent transmission of the network communication. In another embodiment, the application firewall 290 may rewrite, remove or otherwise mask such identified occurrence or confidential information.

Referring now to FIG. 3, an embodiment of the client agent 120 is depicted. The client 102 includes a client agent 120 for establishing and exchanging communications with the appliance 200 and/or server 106 via a network 104. In brief overview, the client 102 operates on computing device 100 having an operating system with a kernel mode 302 and a user mode 303, and a network stack 310 with one or more layers 310 a-310 b. The client 102 may have installed and/or execute one or more applications. In some embodiments, one or more applications may communicate via the network stack 310 to a network 104. One of the applications, such as a web browser, may also include a first program 322. For example, the first program 322 may be used in some embodiments to install and/or execute the client agent 120, or any portion thereof. The client agent 120 includes an interception mechanism, or interceptor 350, for intercepting network communications from the network stack 310 from the one or more applications.

The network stack 310 of the client 102 may comprise any type and form of software, or hardware, or any combinations thereof, for providing connectivity to and communications with a network. In one embodiment, the network stack 310 comprises a software implementation for a network protocol suite. The network stack 310 may comprise one or more network layers, such as any networks layers of the Open Systems Interconnection (OSI) communications model as those skilled in the art recognize and appreciate. As such, the network stack 310 may comprise any type and form of protocols for any of the following layers of the OSI model: 1) physical link layer, 2) data link layer, 3) network layer, 4) transport layer, 5) session layer, 6) presentation layer, and 7) application layer. In one embodiment, the network stack 310 may comprise a transport control protocol (TCP) over the network layer protocol of the internet protocol (IP), generally referred to as TCP/IP. In some embodiments, the TCP/IP protocol may be carried over the Ethernet protocol, which may comprise any of the family of IEEE wide-area-network (WAN) or local-area-network (LAN) protocols, such as those protocols covered by the IEEE 802.3. In some embodiments, the network stack 310 comprises any type and form of a wireless protocol, such as IEEE 802.11 and/or mobile internet protocol.

In view of a TCP/IP based network, any TCP/IP based protocol may be used, including Messaging Application Programming Interface (MAPI) (email), File Transfer Protocol (FTP), HyperText Transfer Protocol (HTTP), Common Internet File System (CIFS) protocol (file transfer), Independent Computing Architecture (ICA) protocol, Remote Desktop Protocol (RDP), Wireless Application Protocol (WAP), Mobile IP protocol, and Voice Over IP (VoIP) protocol. In another embodiment, the network stack 310 comprises any type and form of transport control protocol, such as a modified transport control protocol, for example a Transaction TCP (T/TCP), TCP with selection acknowledgements (TCP-SACK), TCP with large windows (TCP-LW), a congestion prediction protocol such as the TCP-Vegas protocol, and a TCP spoofing protocol. In other embodiments, any type and form of user datagram protocol (UDP), such as UDP over IP, may be used by the network stack 310, such as for voice communications or real-time data communications.

Furthermore, the network stack 310 may include one or more network drivers supporting the one or more layers, such as a TCP driver or a network layer driver. The network drivers may be included as part of the operating system of the computing device 100 or as part of any network interface cards or other network access components of the computing device 100. In some embodiments, any of the network drivers of the network stack 310 may be customized, modified or adapted to provide a custom or modified portion of the network stack 310 in support of any of the techniques described herein. In other embodiments, the acceleration program 120 is designed and constructed to operate with or work in conjunction with the network stack 310 installed or otherwise provided by the operating system of the client 102.

The network stack 310 comprises any type and form of interfaces for receiving, obtaining, providing or otherwise accessing any information and data related to network communications of the client 102. In one embodiment, an interface to the network stack 310 comprises an application programming interface (API). The interface may also comprise any function call, hooking or filtering mechanism, event or call back mechanism, or any type of interfacing technique. The network stack 310 via the interface may receive or provide any type and form of data structure, such as an object, related to functionality or operation of the network stack 310. For example, the data structure may comprise information and data related to a network packet or one or more network packets. In some embodiments, the data structure comprises a portion of the network packet processed at a protocol layer of the network stack 310, such as a network packet of the transport layer. In some embodiments, the data structure 325 comprises a kernel-level data structure, while in other embodiments, the data structure 325 comprises a user-mode data structure. A kernel-level data structure may comprise a data structure obtained or related to a portion of the network stack 310 operating in kernel-mode 302, or a network driver or other software running in kernel-mode 302, or any data structure obtained or received by a service, process, task, thread or other executable instructions running or operating in kernel-mode of the operating system.

Additionally, some portions of the network stack 310 may execute or operate in kernel-mode 302, for example, the data link or network layer, while other portions execute or operate in user-mode 303, such as an application layer of the network stack 310. For example, a first portion 310 a of the network stack may provide user-mode access to the network stack 310 to an application while a second portion 310 a of the network stack 310 provides access to a network. In some embodiments, a first portion 310 a of the network stack may comprise one or more upper layers of the network stack 310, such as any of layers 5-7. In other embodiments, a second portion 310 b of the network stack 310 comprises one or more lower layers, such as any of layers 1-4. Each of the first portion 310 a and second portion 310 b of the network stack 310 may comprise any portion of the network stack 310, at any one or more network layers, in user-mode 203, kernel-mode, 202, or combinations thereof, or at any portion of a network layer or interface point to a network layer or any portion of or interface point to the user-mode 203 and kernel-mode 203.

The interceptor 350 may comprise software, hardware, or any combination of software and hardware. In one embodiment, the interceptor 350 intercept a network communication at any point in the network stack 310, and redirects or transmits the network communication to a destination desired, managed or controlled by the interceptor 350 or client agent 120. For example, the interceptor 350 may intercept a network communication of a network stack 310 of a first network and transmit the network communication to the appliance 200 for transmission on a second network 104. In some embodiments, the interceptor 350 comprises any type interceptor 350 comprises a driver, such as a network driver constructed and designed to interface and work with the network stack 310. In some embodiments, the client agent 120 and/or interceptor 350 operates at one or more layers of the network stack 310, such as at the transport layer. In one embodiment, the interceptor 350 comprises a filter driver, hooking mechanism, or any form and type of suitable network driver interface that interfaces to the transport layer of the network stack, such as via the transport driver interface (TDI). In some embodiments, the interceptor 350 interfaces to a first protocol layer, such as the transport layer and another protocol layer, such as any layer above the transport protocol layer, for example, an application protocol layer. In one embodiment, the interceptor 350 may comprise a driver complying with the Network Driver Interface Specification (NDIS), or a NDIS driver. In another embodiment, the interceptor 350 may comprise a mini-filter or a mini-port driver. In one embodiment, the interceptor 350, or portion thereof, operates in kernel-mode 202. In another embodiment, the interceptor 350, or portion thereof, operates in user-mode 203. In some embodiments, a portion of the interceptor 350 operates in kernel-mode 202 while another portion of the interceptor 350 operates in user-mode 203. In other embodiments, the client agent 120 operates in user-mode 203 but interfaces via the interceptor 350 to a kernel-mode driver, process, service, task or portion of the operating system, such as to obtain a kernel-level data structure 225. In further embodiments, the interceptor 350 is a user-mode application or program, such as application.

In one embodiment, the interceptor 350 intercepts any transport layer connection requests. In these embodiments, the interceptor 350 execute transport layer application programming interface (API) calls to set the destination information, such as destination IP address and/or port to a desired location for the location. In this manner, the interceptor 350 intercepts and redirects the transport layer connection to a IP address and port controlled or managed by the interceptor 350 or client agent 120. In one embodiment, the interceptor 350 sets the destination information for the connection to a local IP address and port of the client 102 on which the client agent 120 is listening. For example, the client agent 120 may comprise a proxy service listening on a local IP address and port for redirected transport layer communications. In some embodiments, the client agent 120 then communicates the redirected transport layer communication to the appliance 200.

In some embodiments, the interceptor 350 intercepts a Domain Name Service (DNS) request. In one embodiment, the client agent 120 and/or interceptor 350 resolves the DNS request. In another embodiment, the interceptor transmits the intercepted DNS request to the appliance 200 for DNS resolution. In one embodiment, the appliance 200 resolves the DNS request and communicates the DNS response to the client agent 120. In some embodiments, the appliance 200 resolves the DNS request via another appliance 200′ or a DNS server 106.

In yet another embodiment, the client agent 120 may comprise two agents 120 and 120′. In one embodiment, a first agent 120 may comprise an interceptor 350 operating at the network layer of the network stack 310. In some embodiments, the first agent 120 intercepts network layer requests such as Internet Control Message Protocol (ICMP) requests (e.g., ping and traceroute). In other embodiments, the second agent 120′ may operate at the transport layer and intercept transport layer communications. In some embodiments, the first agent 120 intercepts communications at one layer of the network stack 210 and interfaces with or communicates the intercepted communication to the second agent 120′.

The client agent 120 and/or interceptor 350 may operate at or interface with a protocol layer in a manner transparent to any other protocol layer of the network stack 310. For example, in one embodiment, the interceptor 350 operates or interfaces with the transport layer of the network stack 310 transparently to any protocol layer below the transport layer, such as the network layer, and any protocol layer above the transport layer, such as the session, presentation or application layer protocols. This allows the other protocol layers of the network stack 310 to operate as desired and without modification for using the interceptor 350. As such, the client agent 120 and/or interceptor 350 can interface with the transport layer to secure, optimize, accelerate, route or load-balance any communications provided via any protocol carried by the transport layer, such as any application layer protocol over TCP/IP.

Furthermore, the client agent 120 and/or interceptor may operate at or interface with the network stack 310 in a manner transparent to any application, a user of the client 102, and any other computing device, such as a server, in communications with the client 102. The client agent 120 and/or interceptor 350 may be installed and/or executed on the client 102 in a manner without modification of an application. In some embodiments, the user of the client 102 or a computing device in communications with the client 102 are not aware of the existence, execution or operation of the client agent 120 and/or interceptor 350. As such, in some embodiments, the client agent 120 and/or interceptor 350 is installed, executed, and/or operated transparently to an application, user of the client 102, another computing device, such as a server, or any of the protocol layers above and/or below the protocol layer interfaced to by the interceptor 350.

The client agent 120 includes an acceleration program 302, a streaming client 306, and/or a collection agent 304. In one embodiment, the client agent 120 comprises an Independent Computing Architecture (ICA) client, or any portion thereof, developed by Citrix Systems, Inc. of Fort Lauderdale, Fla., and is also referred to as an ICA client. Other embodiments of the application client include a Remote Display Protocol (RDP) client, developed by Microsoft Corporation of Redmond, Wash., an X-Windows client, a client-side player, interpreter or simulator capable of executing multimedia applications, email, Java, or .NET code. Moreover, in one embodiment the output of an application executing on the server 106 can be displayed at the client 102 via the ICA client.

In some embodiments, the client 120 comprises an application streaming client 306 for streaming an application from a server 106 to a client 102. In some embodiments, the client agent 120 comprises an acceleration program 302 for accelerating communications between client 102 and server 106. In another embodiment, the client agent 120 includes a collection agent 304 for performing end-point detection/scanning and collecting end-point information for the appliance 200 and/or server 106.

In some embodiments, the acceleration program 302 comprises a client-side acceleration program for performing one or more acceleration techniques to accelerate, enhance or otherwise improve a client's communications with and/or access to a server 106, such as accessing an application provided by a server 106. The logic, functions, and/or operations of the executable instructions of the acceleration program 302 may perform one or more of the following acceleration techniques: 1) multi-protocol compression, 2) transport control protocol pooling, 3) transport control protocol multiplexing, 4) transport control protocol buffering, and 5) caching via a cache manager. Additionally, the acceleration program 302 may perform encryption and/or decryption of any communications received and/or transmitted by the client 102. In some embodiments, the acceleration program 302 performs one or more of the acceleration techniques in an integrated manner or fashion. Additionally, the acceleration program 302 can perform compression on any of the protocols, or multiple-protocols, carried as payload of network packet of the transport layer protocol

The streaming client 306 comprises an application, program, process, service, task or executable instructions for receiving and executing a streamed application from a server 106. A server 106 may stream one or more application data files to the streaming client 306 for playing, executing or otherwise causing to be executed the application on the client 102. In some embodiments, the server 106 transmits a set of compressed or packaged application data files to the streaming client 306. In some embodiments, the plurality of application files are compressed and stored on a file server within an archive file such as a CAB, ZIP, SIT, TAR, JAR or other archive. In one embodiment, the server 106 decompresses, unpackages or unarchives the application files and transmits the files to the client 102. In another embodiment, the client 102 decompresses, unpackages or unarchives the application files. The streaming client 306 dynamically installs the application, or portion thereof, and executes the application. In one embodiment, the streaming client 306 may be an executable program. In some embodiments, the streaming client 306 may be able to launch another executable program.

The collection agent 304 comprises an application, program, process, service, task or executable instructions for identifying, obtaining and/or collecting information about the client 102. In some embodiments, the appliance 200 transmits the collection agent 304 to the client 102 or client agent 120. The collection agent 304 may be configured according to one or more policies of the policy engine 236 of the appliance. In other embodiments, the collection agent 304 transmits collected information on the client 102 to the appliance 200. In one embodiment, the policy engine 236 of the appliance 200 uses the collected information to determine and provide access, authentication and authorization control of the client's connection to a network 104.

In one embodiment, the collection agent 304 comprises an end-point detection and scanning mechanism, which identifies and determines one or more attributes or characteristics of the client. For example, the collection agent 304 may identify and determine any one or more of the following client-side attributes: 1) the operating system an/or a version of an operating system, 2) a service pack of the operating system, 3) a running service, 4) a running process, and 5) a file. The collection agent 304 may also identify and determine the presence or versions of any one or more of the following on the client: 1) antivirus software, 2) personal firewall software, 3) anti-spam software, and 4) internet security software. The policy engine 236 may have one or more policies based on any one or more of the attributes or characteristics of the client or client-side attributes.

In some embodiments and still referring to FIG. 3, a first program 322 may be used to install and/or execute the client agent 120, or portion thereof, such as the interceptor 350, automatically, silently, transparently, or otherwise. In one embodiment, the first program 322 comprises a plugin component, such an ActiveX control or Java control or script that is loaded into and executed by an application. For example, the first program comprises an ActiveX control loaded and run by a web browser application, such as in the memory space or context of the application. In another embodiment, the first program 322 comprises a set of executable instructions loaded into and run by the application, such as a browser. In one embodiment, the first program 322 comprises a designed and constructed program to install the client agent 120. In some embodiments, the first program 322 obtains, downloads, or receives the client agent 120 via the network from another computing device. In another embodiment, the first program 322 is an installer program or a plug and play manager for installing programs, such as network drivers, on the operating system of the client 102.

Communication between a program neighborhood-enabled client 102 and a server 106 or appliance 200 may occur over a dedicated virtual channel that is established on top of an ICA virtual channel. In some embodiments, the communication occurs using an XML service. In other embodiments, the client 102 runs a client-side dialog that acquires the credentials of a user of the client 102. In still other embodiments, a user management subsystem on a server 106 receiving the credentials of the user may return a set of distinguished names representing the list of accounts to which the user belongs. Upon authentication, the server 106 may establish a program neighborhood virtual channel, a control channel, or other communications channel. In yet other embodiments, an acceleration program 302 may also be transmitted to the client 102 in response to a client 102 request.

In some embodiments, a client 102 may use the client agent 120 to browse farm 38, servers 106 and applications in the farm 38. In one embodiment, each server 106 includes an ICA browsing subsystem to provide the client 102 with browsing capability. After the client 102 establishes a connection with the ICA browser subsystem of any of the servers 106, that browser subsystem supports a variety of client 102 requests. Such requests include: (1) enumerating names of servers in the farm, (2) enumerating names of applications published in the farm, (3) resolving a server name and/or application name to a server address that is useful to the client 102. The ICA browser subsystem also supports requests made by clients 102 running a program neighborhood application that provides the client 102, upon request, with a view of those applications within the farm 38 for which the user is authorized. The ICA browser subsystem forwards all of the above-mentioned client requests to the appropriate subsystem in the server 106.

In one embodiment, a user of the client 102 selects an application for execution from a received enumeration of available applications. In another embodiment, the user selects an application for execution independent of the received enumeration. In some embodiments, the user selects an application for execution by selecting a graphical representation of the application presented on the client 102 by a client agent 120. In other embodiments, the user selects an application for execution by selecting a graphical representation of the application presented to the user on a web server or other server 106. In some embodiments, an appliance 200 or acceleration program 302 accelerates delivery of the graphical representation. In some embodiments, an appliance 200 caches or stores the graphical representation. In some embodiments an appliance 200 may cache or store any and all of the associated applications or portions of the associated applications.

In some embodiments, when a client 102 connects to the network 104, the user of the client 102 provides user credentials. User credentials may include the username of a user of the client 102, the password of the user, and the domain name for which the user is authorized. Alternatively, the user credentials may be obtained from smart cards, time-based tokens, social security numbers, user passwords, personal identification (PIN) numbers, digital certificates based on symmetric key or elliptic curve cryptography, biometric characteristics of the user, or any other means by which the identification of the user of the client 102 can be obtained and submitted for authentication. The server 106 or appliance 200 responding to the client 102 can authenticate the user based on the user credentials.

In some embodiments, the client 102 provides credentials upon making a request for execution of an application to a server 106, directly or through an appliance 200. In one of these embodiments, the client 102 requests access to an application residing on a server 106. In another of these embodiments, the client 102 requests access to a network on which a desired resource resides. In other embodiments, the client 102 provides credentials upon making a request for a connection to an appliance 200. In one of these embodiments, the client 102 requests access to a virtual private network. In another of these embodiments, the client 102 requests a network address on the virtual private network. In still another of these embodiments, the client 102 initiates a connection to the appliance 200.

In some embodiments, the user provides credentials to the server 106 or appliance 200 via a graphical user interface presented to the client 102 by the server 106 or appliance 200. In other embodiments, a server 106 or appliance 200 having the functionality of a web server provides the graphical user interface to the client 102. In still other embodiments, a collection agent transmitted to the client 102 by the server 106 or appliance 200 gathers the credentials from the client 102.

In one embodiment, a credential refers to a username and password. In another embodiment, a credential is not limited to a username and password but includes, without limitation, a machine ID of the client 102, operating system type, existence of a patch to an operating system, MAC addresses of installed network cards, a digital watermark on the client device, membership in an Active Directory, existence of a virus scanner, existence of a personal firewall, an HTTP header, browser type, device type, network connection information such as internet protocol address or range of addresses, machine ID of the server 106 or appliance 200, date or time of access request including adjustments for varying time zones, and authorization credentials.

In some embodiments, a credential associated with a client 102 is associated with a user of the client 102. In one of these embodiments, the credential is information possessed by the user. In another of these embodiments, the credential is user authentication information. In other embodiments, a credential associated with a client is associated with a network. In one of these embodiments, the credential is information associated with a network to which the client may connect. In another of these embodiments, the credential is information associated with a network collecting information about the client. In still other embodiments, a credential associated with a client is a characteristic of the client.

In some embodiments, the user authentication performed by the server 106 or appliance 200 may suffice to authorize the use of each hosted application program presented to the client 102, although such applications may reside at another server 106′. Accordingly, when the client 102 launches (i.e., initiates execution of) one of the hosted applications, additional input of user credentials by the client 102 may be unnecessary to authenticate use of that application. Thus, a single entry of the user credentials may serve to determine the available applications and to authorize the launching of such applications without an additional, manual log-on authentication process by the user.

In one embodiment, an appliance 200 receives a request for access to a resource from a client 102. In another embodiment, the appliance 200 receives a request for access to a virtual private network. In still another embodiment, the appliance 200 makes a determination as to whether to grant access and what level of access to grant. In yet another embodiment, the appliance 200 makes a determination as to what type of connection to establish when providing the client with access to the application.

In some embodiments, decisions regarding whether and how to grant a user access to a requested resource are made responsive to determinations by a policy engine regarding whether and how a client 102 may access an application. In one of these embodiments, a decision regarding a level of access is made responsive to a policy engine determination. In another of these embodiments, a decision regarding a type of access is made responsive to a policy engine determination. In still another of these embodiments, a decision regarding a type of connection is made responsive to a policy engine determination. The policy engine may collect information about the client 102 prior to making the determination. In some embodiments, the policy engine resides on the appliance 200. In other embodiments, the appliance 200 is in communication with a police engine residing on a server 106.

Referring now to FIG. 4A, one embodiment of a computer network is depicted, which includes a client 102, a collection agent 404, a policy engine 406, a policy database 408, a farm 38, and an application server 106′. In one embodiment, the policy engine 406 is a server 106. Although only one client 102, collection agent 404, policy engine 406, farm 38, and application server 106′ are depicted in the embodiment shown in FIG. 4A, it should be understood that the system may provide multiple ones of any or each of those components.

In brief overview, when the client 102 transmits a request 410 to the policy engine 406 for access to an application, the collection agent 404 communicates with client 102, retrieving information about the client 102, and transmits the client information 412 to the policy engine 406. The policy engine 406 makes an access control decision by applying a policy from the policy database 408 to the received information 412.

In more detail, the client 102 transmits a request 410 for a resource to the policy engine 406. In one embodiment, the policy engine 406 resides on an application server 106′. In another embodiment, the policy engine 406 is a server 106. In still another embodiment, the policy engine 406 resides on an appliance 200. In yet another embodiment, an application server 106′ or an appliance 200 receives the request 410 from the client 102 and transmits the request 410 to the policy engine 406. In a further embodiment, the client 102 transmits a request 410 for a resource to a server 106″, which transmits the request 410 to the policy engine 406.

Upon receiving the request, the policy engine 406 initiates information gathering by the collection agent 404. The collection agent 404 gathers information regarding the client 102 and transmits the information 412 to the policy engine 406.

In some embodiments, the collection agent 404 gathers and transmits the information 412 over a network connection. In some embodiments, the collection agent 404 comprises bytecode, such as an application written in the bytecode programming language JAVA. In some embodiments, the collection agent 404 comprises at least one script. In those embodiments, the collection agent 404 gathers information by running at least one script on the client 102. In some embodiments, the collection agent comprises an Active X control on the client 102. An Active X control is a specialized Component Object Model (COM) object that implements a set of interfaces that enable it to look and act like a control.

In one embodiment, the policy engine 406 transmits the collection agent 404 to the client 102. In another embodiment, an appliance 200 may store or cache the collection agent 404. The appliance 200 may then transmit the collection agent to a client 102. In other embodiments, an appliance 200 may intercept the transmission of a collection agent 404. In still another embodiment, an appliance 200 may accelerate the delivery of a collection agent 404. In one embodiment, the policy engine 406 requires a second execution of the collection agent 404 after the collection agent 404 has transmitted information 412 to the policy engine 406. In this embodiment, the policy engine 406 may have insufficient information 412 to determine whether the client 102 satisfies a particular condition. In other embodiments, the policy engine 406 requires a plurality of executions of the collection agent 404 in response to received information 412.

In some embodiments, the policy engine 406 transmits instructions to the collection agent 404 determining the type of information the collection agent 404 gathers. In those embodiments, a system administrator may configure the instructions transmitted to the collection agent 404 from the policy engine 406. This provides greater control over the type of information collected. This also expands the types of access control decisions that the policy engine 406 can make, due to the greater control over the type of information collected. The collection agent 404 gathers information 412 including, without limitation, machine ID of the client 102, operating system type, existence of a patch to an operating system, MAC addresses of installed network cards, a digital watermark on the client device, membership in an Active Directory, existence of a virus scanner, existence of a personal firewall, an HTTP header, browser type, device type, network connection information such as internet protocol address or range of addresses, machine ID of the server 106, date or time of access request including adjustments for varying time zones, and authorization credentials. In some embodiments, a collection agent gathers information to determine whether an application can be accelerated on the client using an acceleration program 302.

In some embodiments, the device type is a personal digital assistant. In other embodiments, the device type is a cellular telephone. In other embodiments, the device type is a laptop computer. In other embodiments, the device type is a desktop computer. In other embodiments, the device type is an Internet kiosk.

In some embodiments, the digital watermark includes data embedding. In some embodiments, the watermark comprises a pattern of data inserted into a file to provide source information about the file. In other embodiments, the watermark comprises data hashing files to provide tamper detection. In other embodiments, the watermark provides copyright information about the file.

In some embodiments, the network connection information pertains to bandwidth capabilities. In other embodiments, the network connection information pertains to Internet Protocol address. In still other embodiments, the network connection information consists of an Internet Protocol address. In one embodiment, the network connection information comprises a network zone identifying the logon agent to which the client 102 provided authentication credentials.

In some embodiments, the authorization credentials include a number of types of authentication information, including without limitation, user names, client names, client addresses, passwords, PINs, voice samples, one-time passcodes, biometric data, digital certificates, tickets, etc. and combinations thereof After receiving the gathered information 412, the policy engine 406 makes an access control decision based on the received information 412.

Referring now to FIG. 4B, a block diagram depicts one embodiment of a policy engine 406, including a first component 420 comprising a condition database 422 and a logon agent 424, and including a second component 430 comprising a policy database 432. The first component 420 applies a condition from the condition database 422 to information received about client 102 and determines whether the received information satisfies the condition.

In some embodiments, a condition may require that the client 102 execute a particular operating system to satisfy the condition. In some embodiments, a condition may require that the client 102 execute a particular operating system patch to satisfy the condition. In still other embodiments, a condition may require that the client 102 provide a MAC address for each installed network card to satisfy the condition. In some embodiments, a condition may require that the client 102 indicate membership in a particular Active Directory to satisfy the condition. In another embodiment, a condition may require that the client 102 execute a virus scanner to satisfy the condition. In other embodiments, a condition may require that the client 102 execute a personal firewall to satisfy the condition. In some embodiments, a condition may require that the client 102 comprise a particular device type to satisfy the condition. In other embodiments, a condition may require that the client 102 establish a particular type of network connection to satisfy the condition.

If the received information satisfies a condition, the first component 420 stores an identifier for that condition in a data set 426. In one embodiment, the received information satisfies a condition if the information makes the condition true. For example, a condition may require that a particular operating system be installed. If the client 102 has that operating system, the condition is true and satisfied. In another embodiment, the received information satisfies a condition if the information makes the condition false. For example, a condition may address whether spyware exists on the client 102. If the client 102 does not contain spyware, the condition is false and satisfied.

In some embodiments, the logon agent 424 resides outside of the policy engine 406. In other embodiments, the logon agent 424 resides on the policy engine 406. In one embodiment, the first component 420 includes a logon agent 424, which initiates the information gathering about client 102. In some embodiments, the logon agent 424 further comprises a data store. In these embodiments, the data store includes the conditions for which the collection agent may gather information. This data store is distinct from the condition database 422.

In some embodiments, the logon agent 424 initiates information gathering by executing the collection agent 404. In other embodiments, the logon agent 424 initiates information gathering by transmitting the collection agent 404 to the client 102 for execution on the client 102. In still other embodiments, the logon agent 424 initiates additional information gathering after receiving information 412. In one embodiment, the logon agent 424 also receives the information 412. In this embodiment, the logon agent 424 generates the data set 426 based upon the received information 412. In some embodiments, the logon agent 424 generates the data set 426 by applying a condition from the database 422 to the information received from the collection agent 404.

In another embodiment, the first component 420 includes a plurality of logon agents 424. In this embodiment, at least one of the plurality of logon agents 424 resides on each network domain from which a client 102 may transmit a resource request. In this embodiment, the client 102 transmits the resource request to a particular logon agent 424. In some embodiments, the logon agent 424 transmits to the policy engine 406 the network domain from which the client 102 accessed the logon agent 424. In one embodiment, the network domain from which the client 102 accesses a logon agent 424 is referred to as the network zone of the client 102.

The condition database 422 stores the conditions that the first component 420 applies to received information. The policy database 432 stores the policies that the second component 430 applies to the received data set 426. In some embodiments, the condition database 422 and the policy database 432 store data in an ODBC-compliant database. For example, the condition database 422 and the policy database 432 may be provided as an ORACLE database, manufactured by Oracle Corporation of Redwood Shores, Calif. In other embodiments, the condition database 422 and the policy database 432 can be a Microsoft ACCESS database or a Microsoft SQL server database, manufactured by Microsoft Corporation of Redmond, Wash.

After the first component 420 applies the received information to each condition in the condition database 422, the first component transmits the data set 426 to second component 430. In one embodiment, the first component 420 transmits only the data set 426 to the second component 430. Therefore, in this embodiment, the second component 430 does not receive information 412, only identifiers for satisfied conditions. The second component 430 receives the data set 426 and makes an access control decision by applying a policy from the policy database 432 based upon the conditions identified within data set 426.

In one embodiment, policy database 432 stores the policies applied to the received information 412. In one embodiment, the policies stored in the policy database 432 are specified at least in part by the system administrator. In another embodiment, a user specifies at least some of the policies stored in the policy database 432. The user-specified policy or policies are stored as preferences. The policy database 432 can be stored in volatile or non-volatile memory or, for example, distributed through multiple servers.

In one embodiment, a policy allows access to a resource only if one or more conditions are satisfied. In another embodiment, a policy allows access to a resource but prohibits transmission of the resource to the client 102. Another policy might make connection contingent on the client 102 that requests access being within a secure network. In some embodiments, the resource is an application program and the client 102 has requested execution of the application program. In one of these embodiments, a policy may allow execution of the application program on the client 102. In another of these embodiments, a policy may enable the client 102 to receive a stream of files comprising the application program. In this embodiment, the stream of files may be stored and executed in an isolation environment. In still another of these embodiments, a policy may allow only execution of the application program on a server 106, such as an application server, and require the server 106 to transmit application-output data to the client 102.

Referring now to FIG. 4C, a flow diagram depicts one embodiment of the steps taken by the policy engine 406 to make an access control decision based upon information received about a client 102. Upon receiving gathered information about the client 102 (Step 450), the policy engine 406 generates a data set based upon the information (Step 452). The data set 426 contains identifiers for each condition satisfied by the received information 412. The policy engine 406 applies a policy to each identified condition within the data set 426. That application yields an enumeration of resources which the client 102 may access (Step 454). The policy engine 406 then presents that enumeration to the client 102. In some embodiments, the policy engine 406 creates a Hypertext Markup Language (HTML) document used to present the enumeration to the client.

In some embodiments, a determination is made as to a type of connection to establish when granting access to a resource responsive to a determination by a policy engine such as the policy engine 406 described above in FIG. 4A, FIG. 4B and FIG. 4C. In other embodiments, a determination is made as to a method for granting access to a resource, such as a method for execution, responsive to a determination by a policy engine such as the policy engine 406 described above in FIG. 4A, FIG. 4B and FIG. 4C. In other embodiments, the server 106 or appliance 200 receiving the credentials and the request to execute the enumerated application further comprises such a policy engine 406.

In one embodiment, one of a plurality of types of access is identified, responsive to a policy, each of the plurality of types of access associated with at least one connection characteristic. In one embodiment, the identification is made responsive to an application of a policy to the received credentials associated with the client 102. In some embodiments, the selection is made by a policy engine such as the policy engine 406 described above in FIG. 4A, FIG. 4B and FIG. 4C. In other embodiments, the server 106 or appliance 200 receiving the credentials and the request to execute the enumerated application further comprises such a policy engine 406.

In some embodiments, after a server 106 or appliance 200 authorizes access to a resource, a client 102 performs a pre-launch analysis of the client 102. In one of these embodiments, the client 102 performs the pre-launch analysis to confirm authorization to access a resource, or to complete the authorization process. In other embodiments, the client 102 performs a pre-launch analysis of the client 102 prior to the authorization decision. In still other embodiments, the client 102 performs a pre-launch analysis of the client 102 after receiving authorization to access a resource but prior to the establishment of a connection to the resource. In one of these embodiments, the client 102 performs a pre-launch analysis of the client 102 after receiving authorization to access a resource but prior to an identification of a type of connection authorized for use in accessing the resource.

In one embodiment, the client 102 performs the pre-launch analysis prior to retrieving and executing a resource, such as a plurality of application files comprising an application program. In another embodiment, the client 102 performs the pre-launch analysis responsive to a received indication that the pre-launch analysis is a requirement for authorization to access a resource, such as the plurality of application files comprising an application program. In still another embodiment, the client 102 retrieves at least one characteristic required for execution of an application program. In yet another embodiment, the client 102 receives access information indicating a location of a file for retrieval by the client 102, the file enumerating the at least one characteristic. In some embodiments, the client 102 performs the pre-launch analysis after a server 106 or appliance 200 selects a method of providing access to a resource and identifying a type of connection to establish between the client and the resource.

The client 102 determines the existence of the at least one characteristic on the client 102. In some embodiments, the client 102 makes this determination as part of the pre-launch analysis. In one embodiment, determining the existence of the at least one characteristic on the client 102 includes determining whether a device driver is installed on the client 102. In another embodiment, determining the existence of the at least one characteristic on the client 102 includes determining whether an operating system is installed on the client 102. In still another embodiment, determining the existence of the at least one characteristic on the client 102 includes determining whether a particular operating system is installed on the client 102. In yet another embodiment, determining the existence of the at least one characteristic on the client 102 includes determining whether a particular revision level of an operating system is installed on the client 102.

In some embodiments, determining the existence of the at least one characteristic on the client 102 includes determining whether the client 102 has acquired authorization to execute an enumerated application. In one of these embodiments, a determination is made by the client 102 as to whether the client 102 has received a license to execute the enumerated application. In another of these embodiments, a determination is made by the client 102 as to whether the client 102 has received a license to receive across an application streaming session a plurality of application files comprising the enumerated application. In other embodiments, determining the existence of the at least one characteristic on the client 102 includes determining whether the client 102 has sufficient bandwidth available to retrieve and execute an enumerated application.

In some embodiments, determining the existence of the at least one characteristic on the client 102 includes execution of a script on the client 102. In other embodiments, determining the existence of the at least one characteristic on the client 102 includes installation of software on the client 102. In still other embodiments, determining the existence of the at least one characteristic on the client 102 includes modification of a registry on the client 102. In yet other embodiments, determining the existence of the at least one characteristic on the client 102 includes transmission of a collection agent 404 to the client 102 for execution on the client 102 to gather credentials associated with the client 102.

In some embodiments, the client 102 makes a request for authorization to execute an application responsive to a determination that at least one characteristic exists on the client 102. In one of these embodiments, the client 102 determines that a plurality of characteristics exist on the client 102, the plurality of characteristics associated with an enumerated application and received responsive to a request to execute the enumerated application. In another of these embodiments, whether the client 102 receives authorization for execution of the enumerated application files depends upon existence of the at least one characteristic on the client 102. In one embodiment, the client 102 received an enumeration of application programs, requested execution of an enumerated application, and received access information including the at least one characteristic and a launch ticket authorizing the execution of the enumerated application upon the determination of the existence of the at least one characteristic on the client 102. In some embodiments, the client 102 executes a second client agent 120′, the second client agent 120′ requesting execution of an application on a server 106, responsive to a determination that the client 102 lacks the at least one characteristic.

Referring now to FIG. 5, a screen shot depicts one embodiment of an enumeration of scripts to be executed on the client. In one embodiment, at least one execution pre-requisite is associated with at least one installed application file responsive to an application of a policy to the at least one installed application file or to a characteristic of the installed application file. In another embodiment, a script is associated with the at least one installed application file, the script comprising an executable program determining the existence of at least one execution pre-requisite on a client. A type of script 502 indicates when the script should be executed, for example, either before the execution of the application, or after termination of execution of the application. An isolation indicator 504 indicates whether the script should be executed in an isolation environment on the client 102. As shown in FIG. 5, in some embodiments, the script was associated with the application program at the time a plurality of application files were packaged together and stored on a server 106 hosting the plurality of application files.

In some embodiments, an instruction is associated with the at least one application file, the instruction indicating a second installed application file for use by a client failing to satisfy the at least one execution pre-requisite. In other embodiments, an instruction is associated with the at least one installed application file, the instruction indicating a second execution method for execution of the at least one installed application file on a client failing to satisfy the at least one execution pre-requisite. In one of these embodiments, an execution method is associated with the at least one installed application file, the execution method authorizing streaming of a plurality of application files comprising the second application to a client 102 for execution on the client. In another of these embodiments, an evaluation of a client 102 identifies at least one characteristic associated with the at least one installed application file not included on the client. In still another of these embodiments, authorization for execution of the plurality of application files is revoked. In yet another of these embodiments, a second execution method is provided for executing the plurality of application files, the second execution method enabling execution of the plurality of application files on a server 106 and transmission of application output data from the server 106 to the client.

In another embodiment, the at least one characteristic is added to the client 102 after the pre-launch analysis determines that the client 102 lacks the at least one characteristic. In still another embodiment, the at least one characteristic is included in a server 106 hosting an application program and failure of the client 102 to include the at least one characteristic will prevent execution of the application program. In yet another embodiment, the application program requires existence of the at least one characteristic on the client 102 for execution.

In some embodiments, a packaging mechanism enables identification of at least one characteristic for use in a pre-launch analysis on the client. In other embodiments, the packaging mechanism enables association of at least one characteristic with an application program available for execution on the client. In still other embodiments, the packaging mechanism enables association of an executable script with an application program, the client 102 executing the executable script to complete the pre-launch analysis. In yet other embodiments, the at least one characteristic is required to exist on the client 102 after the execution of the application program.

Referring now to FIG. 6, a block diagram depicts one embodiment of a system for authorizing a level of access of a client to a virtual private network connection based on a client-side attribute. In brief overview, the system includes a client 102, a means for transmitting a request 602, a request 604, an evaluation component 606, a means for transmitting a response 608, a means for receiving an authorization assignment 610, and an appliance 200.

The means for transmitting a request 602 transmits from the client 102 to the appliance 200 the request for a virtual private network connection to a network. In one embodiment, the means for transmitting a request 602 comprises a transmitter. In another embodiment, the means for transmitting a request 602 resides in the client agent 120. In one embodiment, the means for transmitting a request 602 transmits a request for access to a resource, such as an application or server 106, residing on the network. In another embodiment, the means for transmitting a request 602 transmits a request for a network address on the virtual private network. In still another embodiment, the means for transmitting a request 602 transmits the request for the virtual private network connection after authenticating the client 102 to the appliance 200. In yet another embodiment, the means for transmitting a request 602 transmits the request prior to the establishment of a control connection. In a further embodiment, the appliance 200 establishes the control connection responsive to receiving the request from the client 102.

The request 604 is received by the client 102, via a control connection between the client 102 and the appliance 200, for evaluation of at least one clause of a security string, the at least one clause identifying an object for evaluation, an attribute of the object, and a pre-requisite associated with the attribute. In one embodiment, the request 604 includes at least one clause of a security string, the at least one clause identifying the client as an object for evaluation. In another embodiment, the request 604 includes at least one clause of a security string, the at least one clause identifying a presence of an application program on the client as an attribute of the object. In still another embodiment, the request 604 includes at least one clause of a security string, the at least one clause identifying an absence of an application program on the client as an attribute of the object. In yet another embodiment, the request 604 includes at least one clause of a security string, the at least one clause identifying a presence of a version of an application program on the client as an attribute of the object.

In one embodiment, the request 604 includes at least one clause of a security string, the at least one clause identifying an absence of a version of an application program on the client as an attribute of the object. In another embodiment, the request 604 includes at least one clause of a security string, the at least one clause identifying a presence of a required version of an application program on the client as a pre-requisite. In still another embodiment, the request includes at least one clause of a security string, the at least one clause identifying a presence of an application program on the client as a pre-requisite. In yet another embodiment, the request includes at least one clause of a security string, the at least one clause identifying an absence of an application program on the client as a pre-requisite. In some embodiments, the request 604 is sent to the client 102 over the control connection in response to a request by the client for access to a resource or initiation of a connection.

In some embodiments, the kernel on the client 102 receives a security string. In one of these embodiments, the kernel identifies one or more atomic expressions within the security string. In another of these embodiments, the atomic expressions within the security string are separated by logical operators. The logical operators may be expressed by, for example, double ampersands indicating that the expressions are conjunctive or double slashes indicating that the expressions are disjunctive. In still another of these embodiments, the at least one clause of the security string is an atomic expression within the security string separated from other expressions in the security string by logical operators. In other embodiments, and as shown in shadow in FIG. 6, the kernel on the client 102 comprises receiver for receiving the request 604 from the appliance 200 over the control channel. In one of these embodiments, the kernel transmits all or part of the request to the evaluation component 606.

In one embodiment, a user of an appliance 200 generates the security string. In another embodiment, the appliance 200 adds a generated security string as a policy. In still another embodiment, the appliance 200 adds a generated security string as a policy within an authorization server, a policy engine, a firewall, a virtual private network server, or other security appliance. In some embodiments, the appliance 200 transmits the generated security string to the client 102 in its entirety and without re-formatting from the form in which the security string was generated. In other embodiments, the appliance 200 transmits only portions of the security string to the client 102, such as one clause or atomic expression at a time. In still other embodiments, the appliance 200 transmits the generated security string to a kernel on the client 102 for formatting and parsing into atomic expressions.

In one embodiment, a security string is associated with an authorization group. In another embodiment, if a client 102 satisfies a requirement expressed by the security string, the client 102 is assigned to the authorization group. In still another embodiment, if a client 102 fails to satisfy a requirement expressed by the security string, the client 102 is assigned to the authorization group. In some embodiments, if no security string is assigned to an authorization group, the client 102 request is granted without the need for evaluation of a security string. In other embodiments, if no authorization group is assigned to a security string, but evaluation of the security string is required by the appliance 200, the client 102 request is denied.

In one embodiment, a security string is an expression of a policy. In another embodiment, and as an example, if a policy requires a client 102 to execute a particular personal firewall program or a particular antivirus program before accessing a resource or a establishing a type of connection, and if the policy assigns the client to a particular authorization group if the client fails to satisfy the policy, a security string expressing the policy may be of the form: “pf_(—)1_ZoneAlarm_(—)4.0.012.013∥pf_(—)1_TrendMicro_(—)11.0.0”-clientsecurity AuthGroup ag2.” In still another embodiment, and as a second example, a policy may require a particular revision level of an antivirus program and a particular process running, and if the policy assigns the client to a particular authorization group if the client fails to satisfy the policy, a security string expressing the policy may be of the form: “av_(—)0_mcafeevirusscan_(—)4.88 && svc_(—)0_svchost”-cliensecurity AuthGroup ag1.”

In some embodiments, a priority level may be assigned to the security string. In one of these embodiments, the appliance 200 may transmit the security string having the highest priority to the client 102. In another of these embodiments, and as an example, if the appliance 200 identifies the following two security strings:

-   -   sa1-clientsecurity “av_(—)0_mcafeevirusscan_(—)4.88 &&         svc_(—)0_svchost”-cliensecurity AuthGroup ag1     -   sa2-clientsecurity         “pf_(—)1_ZoneAlarm_(—)4.0.012.013∥pf_(—)1_TrendMicro_(—)11.0.0”-clientsecurity         AuthGroup ag2,         the appliance 200 may select the higher priority security string         (sa1) over the lower priority string (sa2). In still another of         these embodiments, when a client 102 connects to a vServer 275         on the appliance 200, the appliance 200 evaluates applicable         security strings and identifies the security string to transmit         to the client 102.

In other embodiments, a security string may be expressed in the form “object.attribute.prerequisite.” In one of these embodiments, and for example, the security string may be an expression identifying the client 102, a particular application program associated with the client 102 and a prerequisite associated with the program, the expression having the following form: client.application[mcafeevirusscan].version>=4.88&& client.svc[svchost]RUNNING In this embodiment, the object is the client 102 (client), the attribute is an antivirus program (application[mcafeevirusscan]), and the pre-requisite is that the application be of at least a particular version level (version>=4.88). In this embodiment, the security string comprises two clauses and the second clause identifies the client 102, a process on the client (a service called svchost), and a pre-requisite associated with the process (that the svchost process be executing, or running, on the client). In this embodiment, the double ampersand indicates that the client must satisfy both of the clauses to satisfy the security string.

In another of these embodiments, and as a second example, the security string may comprise an expression having two disjunctive clauses in which the client 102 may satisfy one clause or the other to satisfy the security string. In one example of this embodiment, the expression may be of the following form: client.application.pf[ZoneAlarm].version>=4.0.012.013∥client.application.pf[TrendMicro].version>=11.0.0. In this embodiment, the client 102 will satisfy the security string if the client 102 executes a particular level of a particular personal firewall (ZoneAlarm version 4.0.012.013 or greater) or if the client 102 executes a particular level of a particular antivirus program (TrendMicro version 11.0.0 or greater).

The evaluation component 606 resides on the client 102, identifies the attribute, determines whether the attribute satisfies the pre-requisite, and evaluates the at least one clause. In some embodiments, the evaluation component 606 resides in the client agent 120. In other embodiments, the kernel of the client 102 provides the functionality of the evaluation component 606. In still other embodiments, the kernel of the client 102 validates a response provided by the evaluation component 606.

In one embodiment, the evaluation component 606 executes a script to evaluate the at least one clause. In another embodiment, the evaluation component 606 is transmitted to the client 102 from the appliance 200. In still another embodiment, the evaluation component 606 is a collection agent, such as a collection agent 404 described above in connection with FIGS. 4A, 4B, and 4C, the collection agent gathering information associated with the attribute. In yet another embodiment, the evaluation component 606 evaluates the at least one clause responsive to the information gathered about the client 102.

In some embodiments, the evaluation component 606 identifies attributes of the client 102. In one of these embodiments, the attributes include, but are not limited to, any of the following: client operating system, presence of service packs, presence of hot fixes on the client, executing services, executing processes, presence of certain files, antivirus software, personal firewall software, anti-spam software, internet security software, and registry configuration. In another of these embodiments, the attributes of the client 102 include information associated with the client, such as the information described in connection with the collection agent 404, described above in connection with FIG. 4A and FIG. 4B. In still another of these embodiments, the attributes of the client 102 include information associated with the client and gathered as part of a pre-launch analysis, as described above.

In one embodiment, the evaluation component 606 identifies an attribute indicating a presence on the client of one of the following: a version of an operating system, a service pack of the operating system, a running service, a running process, and a file. In another embodiment, the evaluation component 606 identifies an attribute indicating a presence on the client of one of the following: antivirus software, personal firewall software, anti-spam software, and internet security software. In still another embodiment, the evaluation component 606 identifies an attribute identifying a version of one of the following: antivirus software, personal firewall software, anti-spam software, and internet security software. In yet another embodiment, the evaluation component 606 determines that the attribute satisfies the pre-requisite responsive to the identification of the attribute.

In some embodiments, as described above, the client 102 performs the pre-launch analysis after a server 106 or appliance 200 selects a method of providing access to a resource and identifying a type of connection to establish between the client and the resource. In other embodiments, the client 102 performs a pre-launch analysis of the client 102 prior to an authorization decision by the appliance 200. In other embodiments, the client 102 performs a pre-launch analysis of the client 102 after receiving authorization to access a resource but prior to the establishment of a connection to the resource. In one of these embodiments, the client 102 performs a pre-launch analysis of the client 102 after receiving authorization to access a resource but prior to an identification of a type of connection authorized for use in accessing the resource.

In some embodiments depicted by FIG. 6 and FIG. 7, the client 102 performs a pre-launch analysis prior to the identification of a type of connection to establish between the client and the resource. In one of these embodiments, the client 102 transmits a result of the pre-launch analysis to the appliance 200. In another of these embodiments, the appliance 200 makes an access control decision, including an identification of a type of connection to establish between the client 102 and a requested resource, responsive to a received result of a pre-launch analysis. In other embodiments, the client 102 evaluates a security string as part of a pre-launch analysis. In still other embodiments, the client 102 transmits a result of a pre-launch analysis to a kernel on the client 102. In yet other embodiments, the kernel evaluates a security string responsive to a received result of the pre-launch analysis.

In some embodiments, the kernel on the client 102 receives the security string. In one of these embodiments, the kernel identifies a plurality of clauses in the security string, the clauses separated by logical operators. In another of these embodiments, the clauses within the string are atomic expressions. In still another of these embodiments, the kernel transmits at least one clause to the evaluation component 606 for evaluation, the at least one clause comprising an atomic expression. In yet another of these embodiments, the evaluation component 606 transmits a result of evaluating the atomic expression to the kernel.

In other embodiments, the kernel on the client 102 receives a result of an evaluation of at least one clause in the security string from the evaluation component 606. In one of these embodiments, the kernel on the client 102 evaluates a security string comprising a plurality of clauses responsive to receiving a plurality of results from the evaluation component 606. In another of these embodiments, the kernel on the client 102 comprises the means for transmitting a response 608. In still another of these embodiments, the kernel on the client 102 transmits a result of an evaluation of an entire security string, comprising a plurality of clauses, to the appliance 200.

The means for transmitting a response 608 transmits from the client 102 to the appliance 200, via the control connection, a response comprising a result of the evaluation of the at least one clause by the evaluation component 606. In one embodiment, the means for transmitting a response 608 transmits a packet to the appliance 200 with the result of the evaluation. In another embodiment, the means for transmitting a response 608 transmits a “1” if the client satisfies the at least one clause or a “0” if the client does not satisfy the at least one clause. In some embodiments, the means for transmitting a response 608 resides on the evaluation component 606. In other embodiments, the means for transmitting a response 608 resides in the client agent 120. In still other embodiments, the means for transmitting a response 608 comprises a transmitter residing in the client agent 120 and sending packets over the control channel.

The means for receiving an authorization assignment 610 receives from the appliance 200 at the client 102 an assignment to an authorization group, the assignment determined based on the evaluation of the at least one clause. In one embodiment, the means for receiving the authorization assignment 610 receives an assignment made responsive to the result of evaluation of a second clause by the appliance 200. In another embodiment, the means for receiving the authorization assignment 610 receives an assignment made responsive to a determination by the appliance 200 that the client 102 lacks a desired attribute. In still another embodiment, the means for receiving the authorization assignment 610 receives an assignment to an authorization group providing quarantined access to the network via the appliance 200.

In some embodiments, the means for receiving an authorization assignment 610 comprises a component residing in the client agent 120. In other embodiments, the means for receiving an authorization assignment 610 resides in a kernel on the client 102. In still other embodiments, the means for receiving an authorization assignment 610 comprises a receiver in communication with the appliance 200.

In some embodiments, an authorization group to which a user of a client 102 belongs is identified by an evaluation of the client 102 and of attributes of the client 102. In one of these embodiments, a user of a client 102 requesting access to a network or other resource, or requesting a connection to a network or a resource on the network, is a member of a group of users, each member in the group authorized to access particular resources via particular types of connections. In another of these embodiments, a user of a client 102 belongs to a default authorization group. In still another of these embodiments, the appliance 200 evaluates the client 102 and determines that although the user of the client 102 is a member of a particular authorization group, the user does not currently satisfy the requirements for membership in the group, and is therefore not authorized to access the resources that the user is typically authorized to use. Alternatively, the appliance 200 may evaluate the client 102 and determine that although the user is not authorized to access particular resources via one type of connection, the client 102 may connect via a different type of connection. In yet another embodiment, the appliance 200 may evaluate the client 102 and determine that although the user is not authorized to access a particular set of resources, the client 102 may access a subset of those resources via a particular type of connection, such as via a secure connection to a quarantined network. In some embodiments, an authorization group may be created for the user of the client 102 upon the evaluation of the attributes of the client 102. In other embodiments, the client 102 satisfies the requirements of the applicable security strings and a connection is established according to the rules or policies of the client 102's default authorization group.

In one embodiment, the means for receiving the authorization assignment 610 receives a denial, from the appliance 200, of the client request if the security string is not associated with an authorization group. In another embodiment, the means for receiving the authorization assignment 610 receives a denial, from the appliance 200, of the client request if a pre-requisite in the security string is not satisfied. In still another embodiment, the means for receiving the authorization assignment 610 receives an assignment made responsive an evaluation, by the appliance 200, of a second clause of the security string comprising one or more logical operations.

Referring now to FIG. 7, a flow diagram depicts one embodiment of the steps taken in a method for authorizing a level of access of a client to a virtual private network connection based on a client-side attribute. In brief overview, an appliance establishes a control connection with a client upon receiving a client request to establish a virtual private network connection with a network (step 702). The appliance transmits, via the control connection, a request to the client to evaluate at least one clause of a security string, the at least one clause including an expression associated with a client-side attribute (step 704). The client transmits, via the control connection, a response to the appliance comprising a result of evaluating the at least one clause by the client (step 706). The appliance assigns the client to an authorization group based on the result of evaluation of the at least one clause (step 708).

Referring now to FIG. 7, and in greater detail, an appliance establishes a control connection with a client upon receiving a client request to establish a virtual private network connection with a network (step 702). In one embodiment, the appliance receives a request from the client to access a resource on a network, such as a file or application. In another embodiment, the appliance receives a request from the client to access a server 106. In still another embodiment, the appliance receives a request for an association between the client and a network address associated with the virtual private network. In yet another embodiment, the client initiates establishment of the control connection. In some embodiments, the appliance is an appliance 200 as described above.

The appliance transmits, via the control connection, a request to the client to evaluate at least one clause of a security string, the at least one clause including an expression associated with a client-side attribute (step 704). In one embodiment, the appliance transmits the request to a collection agent on the client, such as a collection agent 404 described above, the collection agent gathering information associated with the client-side attribute and evaluating the at least one clause. In another embodiment, the appliance transmits a script to the client for execution. In still another embodiment, the appliance transmits a collection agent to the client, the collection agent evaluating the at least one clause.

The client transmits, via the control connection, a response to the appliance comprising a result of evaluating the at least one clause by the client (step 706). In one embodiment, the client evaluates the at least one clause. In another embodiment, a collection agent or evaluation component on the client evaluates the at least one clause. In still another embodiment, the client evaluates the at least one clause by executing a script. In yet another embodiment, the client gathers information associated with the client-side attribute. In a further embodiment, the client evaluates the at least one clause responsive to the gathered information.

In one embodiment, the client identifies a client-side attribute indicating a presence on the client of one of the following: a version of an operating system, a service pack of the operating system, a running service, a running process, and a file. In another embodiment, the client identifies a client-side attribute indicating a presence on the client of one of the following: antivirus software, personal firewall software, anti-spam software, and internet security software. In still another embodiment, the client identifies a client-side attribute indicating a version on the client of one of the following: antivirus software, personal firewall software, anti-spam software, and internet security software.

In one embodiment, the appliance evaluates a second clause of the security string. In another embodiment, the appliance evaluates a clause of the security string comprising one or more logical operations. In some embodiments, the appliance receives gathered information associated with the client. In one of these embodiments, the appliance receives the gathered information from a collection agent, such as a collection agent 404 executing on the client 102 as described above. In another of these embodiments, the appliance evaluates the second clause of the security string responsive to the gathered information.

The appliance assigns the client to an authorization group based on the result of evaluation of the at least one clause (step 708). In one embodiment, the appliance determines that the client lacks a desired client-side attribute, responsive to the result of the evaluation of the at least one clause. In another embodiment, the appliance assigns the client to an authorization group providing quarantined access to the network via the appliance. In still another embodiment, the appliance configures an authorization policy comprising the security string. In yet another embodiment, the appliance assigns the authorization policy to the authorization group.

In one embodiment, the appliance denies a login request from a client if the security string is not associated with the authorization group. In another embodiment, the appliance establishes a virtual private network connection with the client in accordance with the authorization group. In still another embodiment, the appliance establishes a virtual private network connection between the client and a server residing on a virtual private network.

In one embodiment, the appliance assigns the client to an authorization group based on an application of a policy to the result of evaluation of the at least one clause. In another embodiment, the appliance transmits the response comprising the result of the evaluation to a policy engine. In still another embodiment, the appliance assigns the client to an authorization group based on an application of a policy by the policy engine.

The systems and methods described above may be provided as one or more computer-readable programs embodied on or in one or more articles of manufacture. The article of manufacture may be a floppy disk, a hard disk, a CD-ROM, a flash memory card, a PROM, a RAM, a ROM, or a magnetic tape. In general, the computer-readable programs may be implemented in any programming language, LISP, PERL, C, C++, PROLOG, or any byte code language such as JAVA. The software programs may be stored on or in one or more articles of manufacture as object code.

Having described certain embodiments of systems and methods for authorizing a level of access of a client to a virtual private network connection based on a client-side attribute, it will now become apparent to one of skill in the art that other embodiments incorporating the concepts of the invention may be used. Therefore, the invention should not be limited to certain embodiments, but rather should be limited only by the spirit and scope of the following claims. 

1. A method for authorizing a level of access of a client to a virtual private network connection, based on an attribute of a client-side computing environment, the method comprising the steps of: (a) establishing, by an appliance, a control connection with a client upon receiving a client request to establish a virtual private network connection with a network; (b) transmitting, by the appliance via the control connection to the client, a request for an evaluation component executing on the client to evaluate a security string transmitted in the request, the security string comprising one or more expressions including (i) an identifier of an attribute of a client-side computing environment, and (ii) a logical operation on a value of the attribute, a result of which comprises a value that determines what level of access to grant to the client; (c) transmitting, by the client via the control connection, a response to the appliance comprising the result of evaluating the one or more expressions of the security string by the evaluation component; and (d) assigning, by the appliance, a level of access to the client responsive to an application of a policy by a policy engine to the result of the evaluation; and (e) establishing, by the appliance, the virtual private network connection with the client in accordance with the assigned level of access.
 2. The method of claim 1, wherein step (b) further comprises transmitting the request to a collection agent on the client, the collection agent gathering information associated with the identified attribute and evaluating the at least one clause.
 3. The method of claim 1, wherein step (c) further comprises executing, by the client, a script to evaluate the security string.
 4. The method of claim 1, wherein step (c) further comprises gathering, by the client, information associated with the identified attribute.
 5. The method of claim 4, wherein step (c) further comprises evaluating the one or more expressions responsive to the gathered information.
 6. The method of claim 1, wherein step (c) further comprises identifying, by the client responsive to evaluating the at least one clause, a presence on the client of one of the following: a version of an operating system, a service pack of the operating system, a running service, a running process, and a file.
 7. The method of claim 1, wherein step (c) further comprises identifying, by the client, responsive to evaluating the at least one clause, a presence on the client of one of the following: antivirus software, personal firewall software, anti-spam software, and internet security software.
 8. The method of claim 1, wherein step (c) further comprises identifying, by the client, responsive to evaluating the one or more expressions, a version of one of the following: antivirus software, personal firewall software, anti-spam software, and internet security software.
 9. The method of claim 1, wherein step (c) further comprises evaluating, by the appliance, an expression of the one or more expression responsive to identifying that the attribute is present in the client.
 10. The method of claim 1, wherein step (c) further comprises receiving, by the appliance, gathered information associated with the client.
 11. The method of claim 10, wherein step (c) further comprises receiving, by the appliance, the gathered information from a collection agent.
 12. The method of claim 10, wherein step (c) further comprises evaluating the one or more expressions of the security string responsive to the gathered information.
 13. The method of claim 12, wherein step (c) further comprises evaluating, by the appliance, the security string comprising one or more logical operations.
 14. The method of claim 1, wherein step (d) further comprises determining, by the appliance, responsive to the value of the result, that the client lacks the identified attribute.
 15. The method of claim 14, wherein step (d) further comprises assigning, by the appliance, the client to the level of access, the level of access providing quarantined access to the network via the appliance.
 16. The method of claim 1, wherein step (d) further comprises configuring, via the appliance, an authorization policy comprising the security string.
 17. The method of claim 16, wherein step (d) further comprises assigning via the appliance the authorization policy to a level of access or an authorization group.
 18. The method of claim 1, wherein step (d) further comprises denying, by the appliance, a login request from a client if the security string is not associated with a level of access or an authorization group.
 19. The method of claim 1, wherein step (d) further comprises transmitting, by the appliance, to the policy engine, the response comprising the result of the evaluation.
 20. A system for authorizing a level of access of a client to a virtual private network connection, based on an attribute of a client-side computing environment, the system comprising: a means for transmitting, by a client, a request to an appliance for a virtual private network connection to a network; a request received by the client, via a control connection between the client and the appliance, for evaluation of a security string transmitted in the request, the security string comprising one or more expressions including (i) an identifier of an attribute of a client-side computing environment, and (ii) a logical operation on a value of the attribute, a result of which comprises a value that determines what level of access to grant to the client; an evaluation component, executing on the client, for evaluating the one or more expressions; a means for transmitting, by the client via the control connection, a response comprising the result of the evaluation by the evaluation component; and a means for receiving, from the appliance, an assignment of a level of access to the client responsive to an application of a policy by a policy engine to the result of the evaluation, the appliance establishing the virtual private network connection with the client in accordance with the assigned level of access.
 21. The system of claim 20, wherein the security string identifies the client as an object for evaluation.
 22. The system of claim 20, wherein the one or more expressions identifies a presence of an application program as an attribute.
 23. The system of claim 20, wherein the one or more expressions identifies an absence of an application program as an attribute.
 24. The system of claim 20, wherein the one or more expressions identifies a presence of a version of an application program as an attribute.
 25. The system of claim 20, wherein the one or more expressions identifies an absence of a version of an application program as an attribute.
 26. The system of claim 20, wherein the one or more expressions identifies a presence of a required version of an application program as an attribute.
 27. The system of claim 20, wherein the one or more expressions identifies a presence of at least a minimum version of an application program as an attribute.
 28. The system of claim 20, wherein the one or more expressions identifies an absence of at least a minimum version of an application program as an attribute.
 29. The system of claim 20, wherein the evaluation component further comprises a script for evaluating the one or more expressions.
 30. The system of claim 20, wherein the evaluation component is transmitted to the client from the appliance.
 31. The system of claim 20, wherein the evaluation component further comprises a collection agent gathering information associated with the identified attribute.
 32. The system of claim 31, wherein the evaluation component evaluates the one or more expressions responsive to the gathered information.
 33. The system of claim 20, wherein the evaluation component identifies an attribute indicating a presence on the client of one of the following: a version of an operating system, a service pack of the operating system, a running service, a running process, and a file.
 34. The system of claim 20, wherein the evaluation component identifies an attribute indicating a presence on the client of one of the following: antivirus software, personal firewall software, anti-spam software, and internet security software.
 35. The system of claim 20, wherein the evaluation component identifies an attribute indicating a presence on the client of a version of one of the following: antivirus software, personal firewall software, anti-spam software, and internet security software.
 36. The system of claim 20, wherein the evaluation component determines that the identified attribute satisfies a pre-requisite included in the security string.
 37. The system of claim 20, wherein the means for receiving further comprises a means for receiving an assignment made responsive to the result of evaluation of a second clause by the appliance.
 38. The system of claim 20, wherein the means for receiving further comprises a means for receiving an assignment made responsive to a determination by the appliance that the client lacks a desired attribute.
 39. The system of claim 38, wherein the means for receiving further comprises a means for receiving an assignment to the level of access, the level of access providing quarantined access to the network via the appliance.
 40. The system of claim 20, wherein the means for receiving further comprises a means for receiving a denial, by the appliance, of the client request if the security string is not associated with an authorization group or a level of access.
 41. The system of claim 20, wherein the means for receiving further comprises a means for receiving a denial, by the appliance, of the client request if a pre-requisite in the security string is not satisfied.
 42. The system of claim 20, wherein the means for receiving further comprises a means for receiving an assignment made responsive to an evaluation, by the appliance, of another expression of the security string comprising one or more logical operations. 